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                            FRESHWATER FISH POND  
                           CULTURE AND MANAGEMENT

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                      1600 WILSON BOULEVARD, SUITE 500
                       ARLINGTON, VIRGINIA 22209, USA
                            FRESHWATER FISH POND
                           CULTURE AND MANAGEMENT

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                              FRESHWATER FISH POND
                             CULTURE AND MANAGEMENT
                              [C] VITA, 1976
                           May be reproduced without
                           payment of royalty for official
                           U.S. Government purposes.
About this manual....
Freshwater Fish Pond Culture and Management is the second in a series
of publications being prepared by the United States Peace Corps and
VITA, Volunteers in Technical Assistance.   These publications combine
Peace Corps' practical field experiences with VITA's technical expertise
in areas in which development workers have special difficulties finding
useful resource materials.
Since 1961 Peace Corps Volunteers have worked at the grass roots level
in countries around the world in program areas such as agriculture,
public health, and education.   Before beginning their two-year assignments,
Volunteers are given training in cross-cultural, technical,
and language skills.  This training helps them to live and work closely
with the people of their host countries.   It helps them, too, to
approach development problems with new ideas that make use of locally
available resources and are appropriate to the local cultures.
Recently Peace Corps established an Information Collection & Exchange
so that these ideas developed during service in the field could be made
available to the wide range of development workers who might find them
useful.  Materials from the field are now being collected, reviewed,
and classified in the Information Collection & Exchange system.  The
most useful materials will be shared.   The Information Collection &
Exchange provides an important source of field-based research materials
for the production of how-to manuals such as Freshwater Fish Pond Culture
and Management.
VITA people are also Volunteers Who respond to requests for technical
assistance.  In providing solutions, their aim is the most appropriate
answers for specific situations.   Therefore, VITA specialists often must
produce new designs or adapt technologies so that they are of value
in developing areas.
Many VITA Volunteers have lived and worked abroad.   Most VITA people now
work in the United States and other developed countries where they are
engineers, doctors, scientists, farmers, architects, writers, artists,
and so on.  But they continue to work with people in other countries
through VITA.  Thanks to their contributions of time and expertise, VITA
has been providing technical assistance to the Third World for more than
15 years.
Requests for technical assistance come to VITA from many nations.  Each
request is sent to a Volunteer with the right skills.   For example, a
question about fish pond operation might be sent to a VITA Volunteer who
has had years of experience working to develop fish ponds in Asia, and
who is now a university professor.
Freshwater Fish Pond Culture and Management is a how-to manual.  It is
designed as a working and teaching tool for extension agents.  It is for
their use as they establish and/or maintain local fish pond operations.
The information is presented here to 1)   facilitate technology transfer
and 2)  provide a clear guide for warm water fish pond construction and
management.  A valuable listing of resources at the end of this manual
will give further direction to those wishing more information on various
aspects of fish pond operation.
The strength of both Peace Corps and VITA lies in Volunteers.  These
manuals represent an excellent means of communicating important know-how
gained through Volunteer experiences and inputs.
The author of Freshwater Fish Pond Culture and Management, Marilyn
Chakroff, served with Peace Corps in the Philippines for three years
in a number of fisheries programs.   Ms. Chakroff, who holds a B.S. in
Biology, now is an advanced degree candidate in the field of Environmental
Communications at the State University of New York, in Syracuse.
This manual is written out of her first-hand experience as a Peace
Corps Volunteer.
Joan Koster, the illustrator, has been a VITA Volunteer for more than 3
years.  She is a teacher, professional artist, and writer.  Ms. Koster,
who has travelled and studied in Greece for a number of years, currently
is preparing a manuscript on looms and weaving.
Many thanks are due here to a number of people who aided the preparation
of this manual:
Dr. David Hanselman, Dr. Peter Black, and Dr. Robert Werner -- Faculty
of the College of Environmental Science and Forestry, State University of
New York, Syracuse, New York.
Dr. Shirley Crawford, Agricultural and Technical College, State University
of New York, Morrisville, New York.
William McLarney, New Alchemy Institute, Woods Hole, Massachusetts.
A.F. D'Mello, Hawkesbury Agricultural College, New South Wales,
Richard T. Carruthers, Bioproducts, Inc., Warrenton, Oregon.
Dr. William Ribelin, Department of Veterinary Science, University
of Wisconsin, Madison.
A special note of thanks is due John Goodell, VITA, for his layout work
and staff assistance with this manual.
For your convenience, a reply form has been provided here.  Please
send it in and let us know how the manual has helped or can be made
more helpful.  If the reply form is missing from your copy of the
manual, just put your comments, suggestions, descriptions of problems,
etc., on a piece of paper and send them to:
                 1600 Wilson Boulevard, Suite 500
                  Arlington, Virginia 22209 USA
                Tel:  703/276-1800 * Fax:   703/243-1865
                        PLEASE RETURN THIS FORM
NOTE TO THE USER:  This manual was published because Peace Corps and
VITA workers and volunteers wish to help in a growing area of worldwide
interest.  In order to provide the most effective help, the preparers
of the manual need to know how it is being used, or how you feel it could
better serve your needs.  Please fill in the following form and return
it to:
                 1600 Wilson Boulevard, Suite 500
                  Arlington, Virginia 22209 USA
                Tel:  703/276-1800 * Fax:   703/243-1865
   *   Updates and/or additions and corrections to the manual as
      they become available.
   *   Notice of other publications which may be of interest to you.
If you have questions on the material presented in the manual, or if
you run into problems implementing the suggestions offered here, please
note them in the space provided.   Use additional paper if you have to
in order to be as specific as you can about the problem.  Wherever
possible, we will try to provide or direct you to an answer.
                               *      *     *
                                     Date ________________________
                                     Your Company or
Your Name ________________________    Agency, if any ______________
Your Address _____________________________________________________
1.  How did you find out about the PC/VITA Freshwater Fish Pond Culture
    and Management manual?  How did you get your copy?
2.  Which parts of the manual have you found most useful?  Least useful?
3.  Did you find the manual easy to read, too simple or too complex,
    complete or incomplete?
4.  How has this manual helped your work?  What have you done to apply
    the information?
5.  Which plans have you used?  Did you make changes in any of the plans?
    (For example, when you were building a drainage system, did you
    substitute any materials for the ones mentioned or change the design?)
    If you made changes, please describe what you did that was different.
    Include photos, sketches, etc., if possible or important.
6.  Can you recommend additional methods or equipment which you feel
    should be included in a new edition of the manual?  If you do know
    of such methods, etc., please include the information here.
7.  What were your successes using the manual or implementing any of the
     plans or procedures?   Problems?  Please describe completely.
8.  Do you have other recommendations?
Privacy Act Notice:  Furnishing tile information requested herein is
completely voluntary.  It is requested under authorities contained in
the Peace Corps Act (22USC 2501 et seq.).   The only uses which will be
made of this information are as follows:   1)  For management purposes
involving the format of future issues of this publication; 2)  For incorporation
in a mailing list for this other similar publications.
                           Table of Contents
           "About This Manual"                                       
           Reply Form                                                
  1         INTRODUCTION                                               
  2         PLANNING:   THE SITE AND THE TYPE OF FISH FARM              
  3         PLANNING:   SELECTION OF FISH                               
  4         FISH POND CONSTRUCTION                                     
  5         PREPARING THE POND                                        
  6         MANAGING THE POND                                         
  7         HARVESTING THE POND                                       
  8         PRESERVING FISH                                            
  9         PROBLEMS OF FISH IN PONDS                                
 10         OTHER METHODS OF FISH CULTURE                             
           Measurements Used in This Manual                          
1           Introduction
What is Fish Culture?
Fish culture is the growing of fish in ponds.   Growing fish in ponds,
from which they cannot escape, allows feeding, breeding, growing, and
harvesting the fish in a well-planned way.
Fish culture is one form of aquaculture.   Aquaculture is the science
which deals with methods of growing (cultivating) animal and vegetable
life in water.  Some other kinds of aquaculture are concerned with growing
frogs, oysters, seaweed, and even rice.

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History of Fish Culture in Ponds
Growing fish in ponds is a very old practice.   Carp were cultured as long
ago as 2698 B.C. in China, where they were grown in ponds on silkworm
farms.  Fish culture seemed to occur whenever civilization was settled
for a long period of time.  For example, fish culture was done in ancient
Egypt and in China, which has had a continuous civilization for over
4,000 years.  The first written account of fish culture in ponds was by
Fan Lai, a Chinese fish farmer, in 475 B.C.
The ancient Romans introduced carp from Asia into Greece and Italy.  By
the seventeenth century (1600's), carp culture was being done all over
Europe.  A book written in England in 1600 by John Taverner gives the
details of good pond management and talks about growing the common carp.
Taverner also wrote about pond construction, fertilization and feeding.
Another book, written in 1865, gave the details of the stripping methods
of spawning fish.  The methods of culturing common carp have not changed
very much since that time.
The common carp is still a very important pond fish.   In addition,
today, other fish also are being cultured in ponds.   Some of the most
well-known are fish of the tilapia genus, like Tilapia nilotica and
Tilapia mossambica.  Some of the other Chinese carps -- the silver, grass,
and bighead carps -- also are often used in pond culture.  Most importantly,
countries all over the world are using time and money to discover which
of the fish commonly found in their own waters will grow well in fish
Why Fish are Grown in Ponds
The practice of culturing fish in ponds developed because growing fish in
ponds is a more useful practice, for some purposes, than trying to catch
fish from lakes, rivers, or streams.   For example:
   *   Many interested people discover that building a fish pond
      close to home is possible and far more convenient than going
      to the nearest market or river.  Ponds can be built wherever
      the soil, shape of the land, and water supply are right.  This
      may sound as if a lot of factors are involved.  But since a
      wide variety of soils, land shapes, and water supplies can be
      used for pond culture, a fish pond can even be made from a
      rice paddy or an unused grain field.
   *   It is easier to get fish out of a pond than it is to catch a
      fish from a river or stream.  Also, the number of fish taken
      out of a pond can be controlled.  But it is very difficult to
      know how many fish can be caught in a river or stream or lake
      at any one time.  When the farmer goes to his fish pond to get
      dinner, he knows he can take out the number of fish he needs
      -- quickly and easily.
   *   Fish growth can be controlled.   The fish can be fed extra
      food to make them better for market; natural enemies can
      be kept from killing the fish.  For a person who relies on
      fish for his food or his income, these are important factors.
   *   The only fish grown in a pond are the ones the farmer
      wants to grow.  When he takes a fish out of his pond, the
      farmer knows what kind or kinds he will be getting.  When
      he catches fish in a lake,
      stream, or river, many of the
      fish will not be the ones that
      are good to eat or to sell.
   *   Growing fish in ponds allows
      the farmer, or other fish
      grower, to produce fish
      cheaply, and to have a supply
      of fish available on his own
      land.   Fish in ponds belong
      to the pond owners; fish in
      the rivers and lakes do not.

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Why Growing Fish is Important
There are some very good reasons why a farmer or small land owner might
be interested in fish farming:
   *   Fish are an important food source.
   *   Fish farming can help a farmer make the best use of his land.
   *   Fish farming can provide extra income.
There may be additional reasons; you and the pond owners can determine
these from the local situation.   The three points listed above are very
broad, however, and apply, at least in part, to most situations.
Therefore, each point is discussed more fully below.
FISH AS FOOD  Farmers know that all living things need food, and that
without food, living things die.   However, they are not as likely to know
the characteristics of food which make it valuable (or not) to the body.
Food is important because it provides proteins, vitamins, minerals, fats,
and carbohydrates.  These things are called nutrients:  they are materials
that the body must have to live and grow.   Every kind of food has different
amounts of each of these nutrients.   For example, some foods
contain more protein; others have more fat than protein.

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Because foods contain different amounts
of proteins, fats, and carbohydrates,
for example, it is necessary to eat a
number of different kinds of food to
get the right amounts of each nutrient.
All the foods together then give the
body what it needs to grow.
The food that people eat is called
their diet.  Eating the right kinds of
food -- foods that give the body the
right amounts of proteins, fats, etc.
-- is called eating a balanced diet.
People who eat a balanced diet usually
are healthy and strong; people who do
not eat the right kinds of food are
more likely to be weak and get sick.
Proteins are the most important part of food.   Protein is made of carbon,
hydrogen, and nitrogen.  These are called elements.  The combinations of
elements in protein make it the most useful nutrient.   Foods that contain
a lot of protein are especially good for people to eat.   And fish contains
a lot of protein.
The table on the opposite page shows a list of foods that humans eat.
The first number beside the food shows the number of grams of protein in
the food when it is fresh.  The second number tells how many grams of
protein there are in food which has been dried.   The table shows that
fish -- whether fresh or dried -- is a very good source of protein.
(100gm of dried fish contains more protein than 100gm of fresh fish only
because dried foods have water taken out.   Therefore, 100gm of fresh fish
weighs less when it is dried.)

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If the farmers in your area already eat a lot of fish, or like fish, fish
farming for food may not be hard to introduce and have accepted.
If they do not eat fish often, you will have to keep this in mind when
you talk about fish as a healthy food.   Food just may not be the most
important reason, from their point of view, for wanting to grow fish.
                                Fresh, gms protein         Dried, gms protein
Food                                 per 100gm                  per 100gm
Fatty (herring)                           17                       46
Non-fatty (haddock)                       16                       84
Beef                                      20                       67
Pork, loin                                20                       67
Liver                                     20                       67
Milk                                       3.4                     26
Eggs                                      12                       46
Wheat                                    12                       14
Maize                                     10                       11
Oats                                      10                       11
Rice                                       8                        9
Soya                                      33                       37
Cottonseed                                20                       21
Sesame                                    21                       22
Cabbage                                    1.4 - 3.3               24
Spinach                                    2.3 - 5.5               26
Cassava (manioc )                          0.7                      2
Potatoes                                   2.1                      9
Yams                                       2.1                      7
Plantains                                  1.0                      3
          (*) These values are estimates only; the amount
              of protein varies according to the age, size,
              and quality of the food, and how it was
              cooked and stored.
Source:  Aylward and Jul (1975)
But there are other reasons you can offer a farmer.   For example, a
farmer may consider cultivating fish if he realizes that fish are easy
to grow, cheaper than some kinds of meat, available as food all year
round, etc.  You will have to see which combination of arguments works
best for getting farmers interested.
BETTER LAND USE  Some farmers may be more interested in fish farming
when they realize they can accomplish two purposes:   provide a reliable
food supply and make the best possible use of their land.
"Fish farming" is a good thing to call "fish culture" because it can
start the farmer thinking about raising fish with the same kind of planning
and land-use management ideas that he puts into raising crops.
Whether the farmer raises fish, crops, or animals, he is using his land
in certain ways.  His aim in all cases is to increase the production of
food and the yield from the land.   What farmers, and other people, often
do not realize is that fish culture can help get more out of the land.
Here are a few ways in which fish culture can help support and extend a
farmer's land use:
   *   Land gets tired when it is used for growing the same crop
      year after year.  These crops use up nutrients in soil, and
      they begin to grow poorly.  Fish ponds can be built on this
      land and fertilized to provide food for the fish.  After a
      few years of fertilizing and growing fish, the soil inside
      the pond regains some of the nutrients used up by the growing
      of crops year after year.  The land can then be used for
      crops again.
   *   Some farmers own land that may not be very good for growing
      crops:   it is too sandy, for example.   But there are ways of
      building fish ponds in sandy soil.  So the farmer would be
      able to use land that was once not of much value to him.
   *   There are many ways that fish farming can fit into the
      farmer's plan for his land.  The important thing is that all
      of these ways help the farmer make the best use and get more
      out of what he has -- readily, and often without much expense.
      For example, a farmer who grows paddy rice can grow fish in
      that paddy; fish ponds can be built as part of water supply
      and irrigation systems; vegetable scraps and animal manures
      can be collected and used for fertilizing ponds.  The farmer
      should know that a farm with a fish pond or ponds can give
      a total food yield that is higher than a farm with no fish
The following diagram illustrates some of the ways in which the fish
pond fits into the farm:  The same water source is used by both the
garden and the fish pond; the mud from the bottom of the pond makes
good fertilizer for the garden; vegetable matter from the garden can be
used to fertilize fish ponds; manure from the animals can be used for the
pond and parts of fish can be used to feed animals; etc.

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ADDED INCOME  Fish ponds can be quite small, or they can be large.
They can be made using expensive equipment and drainage systems, or they
can be dug using hand tools and drained by a bamboo pipe.  Fish can grow
successfully in both of these types of pond, as long as the ponds are
managed correctly.
If the major reason for building the fish pond is to get increased and
better food for his family, a farmer certainly does not need fancy ponds
or expensive equipment.  Fish ponds can be very inexpensive to keep.
Fish do not require fancy foods.   Many ponds provide all the food the
fish need.  But besides the foods they find in water itself, some fish
eat leafy garbage, mill sweepings, beer residues, spoiled grains, broken
rice, and many other waste products that might not otherwise be used.
A farmer makes his income go further by growing more of the family's
food and by selling leftover fish the family cannot eat.

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Growing fish to sell can also be
very profitable.  But the costs
involved in getting started and in
maintaining the effort are greater:
if the farming is to be a solid
commercial enterprise, then more
ponds, more time, more money, and
nearby marketplaces are needed.
The business may or may not show
a profit right away; in fact, the
chances are that it will not.   A
farmer might be better advised to
start small and work into a bigger
enterprise slowly as he learns to
manage the art of growing fish in
A Word about Cooperation
Often fish ponds are built by cooperatives.   A cooperative is an organization
of people in an area who come together to do something they could
not or would not do alone.  In this way, four or five people or families
can pool their resources and build a fish pond operation together.
Sometimes an entire village will form a cooperative and will build and
operate a pond as a group.  This kind of cooperation makes possible
better pond construction and management.   A fish pond cooperative may be
a good way for a village to improve the diet of the community and to sell
enough fish to maintain the enterprise.   If the farmers in your area are
not interested in, or are concerned about, building ponds individually,
a cooperative may be a very acceptable idea.

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Getting Ready to Plan a Fish Farm
A farmer or other person interested in growing fish should read the
following list carefully before going further.   The following factors
must be considered before the farmer builds his fish pond.  Many pond
owners have small fish ponds that are only used for their own families,
but a farmer who sells fish must look for a market and a way to get his
fish to that market.  It does no good to harvest fish which cannot be
sold or used by the farmer and his family.
   *   Is the soil able to hold water for a fish pond?
   *   Is there an adequate supply of water for a pond?
   *   Is the land a good shape for a fish pond?
   *   Is the pond area close to your home?
   *   Who owns the land where the pond will be built?
   *   Are there enough people to help build and harvest the pond?
   *   Can the equipment for building a pond be built, borrowed, or bought.
   *   Is there a marketplace nearby?
   *   Are there roads from the pond area to a market place?
   *   Are the roads passable even in the rainy season?
   *   Is there a good way to get the fish to market?
   *   Is there a vehicle available for transportation, if necessary?
   *   If there is no market nearby, or if it is hard to get to the
      market, can the fish be kept by drying, smoking, or salting?
   *   Is there enough food for the pond fish?
   *   Are there fertilizers available?
   *   Do the people in the area like fish?   Do they eat freshwater fish?
   *   Can the people in the area afford to buy the fish produced in the
If the farmer can answer yes to the questions which most fit his
situation, he has a good chance of having a successful fish pond.
But he must consider these factors.   Each is discussed in detail in
the "Planning" sections.
2           Planning:   The Site and the
            Type of Fish Farm
Before construction can begin, the farmer must look over his land to
choose the place or places where ponds can be built, and decide what
kind and how many to build.  He must also decide on the kind of fish
culture he wants to do, and on the type of fish that he wants to raise.
He must look at his resources and his needs very carefully before he
actually begins building and operating a fish pond.   This section will
give information to guide the farmer in the planning of ponds and kind
of fish culture.

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The Site
One of the most important parts of planning is finding the right place
(selecting the site) for the pond.   Fish ponds use the land in a different
way from agricultural crops such as rice or wheat, but fish also are a
crop.  And when a farmer builds a fish pond, he is choosing one use of
his land instead of some other use.   If the site for the pond is well-chosen,
the pond can be more productive than the land by itself.  But if
it is not chosen well, the farmer may lose, or, at best, gain nothing
from his fish pond.  When considering a site for the fish pond, the
farmer should remember and consider several points that were made in the
   *   Often poor agricultural land can be turned into very good fish
      ponds.   In general, the better the soil of an area, the better
      the fish pond.  But this does not mean that a pond cannot be
      built on   poor land.  It does mean that the farmer will have to
      work harder to maintain the pond and the fish.
   *   If the pond is built on agricultural land which is not producing
      good crops, but the pond is cared for well, eventually the pond
      bottom soil will become more fertile than it was before.  If
      this pond is a large one, after harvesting the fish, the pond
      can be planted again with a land crop, like corn, and allowed
      to grow.   Then when the corn is harvested, the land can be
      turned back into a fish pond.  This means that a farmer can get
      two good uses out of his land instead of one poor crop.
   *   Other farmers may want to grow fish in rice paddies by digging
      trenches around the edges of the paddy for fish to swim in.
      This is another way of culturing fish which will be discussed
      in somewhat more detail later in the manual.
The point of the discussion above, is that a fish pond is just one use
that a farmer's fields can have, and the choice of how the land can be
used is important.

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There are three factors that work together to make a good site for a
fish pond:
   *   Water supply
   *   Soil
   *   Topography
WATER SUPPLY  Water supply, soil, and topography all are important,
but water supply is the most important factor in selecting a site.  Fish
depend upon water for all their needs:   fish need water in which to
breathe, to eat, and to grow and reproduce.   If a site has water available
year-round, that site meets its first test easily.   If water is not
available all the time but there is some way to store water -- in large
tanks, barrels or drums, in depressions, ponds, or wells -- for use when
the natural water supply is low, then that site may still be all right.
The key, of course, is that water must be available at all times and in
good supply.
Where Can Water for Fish Ponds Come From?   Water used in ponds comes
from many sources:
   *   Rainfall.  Some ponds, called "sky" ponds, rely only on rainfall
      to fill their need for water.
   *   Run-off.  Some ponds are gravel and sand pits which fill when
      water from the surrounding land area runs into them.
   *   Natural waters.   Most ponds are filled with water that comes
      from natural springs or wells, or with water that has been
      channelled (diverted) and brought in from streams, rivers,
      or lakes.
   *   Springs.  Some ponds are built where there is a spring to supply
      water.   Spring water is water under the ground that has found a
      way to get out.  It leaves the ground and becomes a stream as it
      flows away.   Spring water is good for fish ponds because it is
      usually clean (uncontaminated) and has no unwanted fish or fish
      eggs in it.  If the water from a spring has travelled very far,
      it may need to be filtered before it is used for a fish pond.
      But filtering is easy to do (see the "Construction" section)
      and the important fact is that the water supply is available.

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   *   Wells.  The best source of water for a fish pond is well water.
      Well water has few contaminants and, if the well is a good one,
      the water is continuously available.  Well water and spring
      water, however, are both often low in oxygen content.  Fish
      need to have oxygen in their water to live.  Since this problem
      is overcome easily (see water quality information in the section
      on "Preparing the Pond") the major factor to be considered
      here is an adequate water supply.
Most fish ponds use water that comes from a stream, river, or lake.
A diversion ditch or channel is dug between the water source and the
pond to take water from source to pond.   This is a good way to fill a
pond because the water can be controlled easily.   When the pond is full,
the channel can be blocked with a gate or a plug (see "Construction"
section), and the water will stop moving into the pond.
There can be problems with this kind of water supply; for example, often
in tropical areas streams flood in the rainy season.   This extra water
can be dangerous to the pond and must be diverted away from the pond by
a channel built for that purpose.   IT IS BEST NOT TO CHOOSE A PLACE THAT
a pond floods, all the fish escape, and the pond is empty at harvest time.
If the water for the pond is being taken from a stream, lake, or river,
then the farmer should plan to filter the water carefully when filling
the pond.  Water from these sources sometimes contains unwanted fish or
fish eggs.  Filtering prevents these fish or eggs, and other harmful
animals, from entering the pond.
Quality of the Water Supply.   Finding an adequate water supply is the
first step.  Then the farmer has to check that supply to make sure it
can be used for a pond.  This check of the water should include:
   *   looking at the water, smelling it and tasting it.
   *   looking to see if there is a family upstream who take baths in
      the water before it gets to the pond.
   *   making sure that there is no family or village downstream that
       depends upon the source for their drinking water.
If the water supply seems all right, the farmer must also find the
answers to some other questions.   Where the water comes from, how far it
travels to get to the site for the pond, and what kind of soil it travels
over will all affect the quality of the water.   These questions and their
answers tell what must be done to make the water right for a pond:
   *   Is the water very clear?   Then the farmer may have to fertilize
      the pond because there are not enough nutrients in the water.
   *   Is the water very muddy?   Then it will have to settle before it
      is used in the pond:  a special place will have to be made
      where the mud can settle out of the water before the water
      goes into the pond.
   *   Is the water a bright green?   It probably has a lot of fish
      food in it.
   *   Is the water a dark, smelly brown?   It may have acid in it,
      and the farmer will have to add lime to the water.
There are many things which can be done to make water good for a pond.
If the farmer knows his supply and the kind of water he has, he can
take the steps necessary to use his supply well.
SOIL  The second important part of site selection is the soil of the
area.  The soil of the pond must be able to hold water.  It also contributes
to the fertility of the water because of the nutrients it
Ability of Soil to Hold Water.   The best soil for a pond contains a lot
of clay.  Clay soil holds water well.  When a place with a good water
supply is found, the farmer must test the soil.   He can tell a lot about
the soil simply by feeling it.   If the soil feels gritty or rough to the
touch, it probably contains a lot of sand.   If it feels smooth and
slippery, it probably means there is a lot of clay in it.  This smooth
soil is good for a fish pond.
      A very good way to tell if the soil is right for a fish
      pond is to wet a handful of soil with just enough water
      to make it damp.

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      Then squeeze the soil.

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      If it holds its shape when the farmer opens his hand, it will
      be good for a pond.  Remember, the more clay in the soil, the
      better it is for building a pond.

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If the soil is sandy, or does not contain much clay, the farmer can still
build a pond.  There are ways of building ponds in these soils.  But he
should be aware that building a fish pond in such soils requires more
effort and may not be as successful.   Digging test holes will tell the
farmer what his soil is.
Larger ponds can be built in soils with clay.   If the soil is rocky or has
shifting sand, etc., only small ponds are possible.   If there are other
locations available, the farmer would be wise to see if there is another
place with soil better suited to the fish pond.   More information on soil
is included in the "Construction" section.
Ability of Soil to Provide Nutrients.   Soil also contributes to the pond's
fertility.  Fertility is a measure of the nutrients in the pond, and it
simply refers to how much food there is available in the pond for the
fish to eat.  A very fertile pond is one which contains a lot of fish food.
The soil of the pond contains some of these necessary nutrients -- like
iron, calcium, and magnesium.   In addition, however, soil also can contain
acids; these substances often are harmful to fish.   Whatever a soil has
in it is drawn into the pond by the water and thus comes in contact with
the fish.  Sometimes after a heavy rainstorm, there are big fish kills
in new ponds.  This happens because the heavy rain carries larger
amounts of acids from the soil into the pond.   So the farmer who is aware
of the kind of soil he has for his fish pond can prevent this problem
before it happens.
REMEMBER:  One good indicator of the quality of soil is whether it has
been used for growing crops.   If crops grow well in that location, the
soil will probably be good for the fish pond.   If crops did grow well
there before the nutrients were used up, then it will probably still be
free of harmful substances.
TOPOGRAPHY  The third factor in site selection is topography.
Topography is a word used to describe the shape of the land -- whether
it is flat or hilly, upland or lowland, etc.   The topography of the land
determines the kinds of ponds which can be built.   Ponds can be built in
valleys or on flat ground.  They can be square or rectangular, or uneven
in shape.  They can be large or small.  All of this is determined by
topography of the land, as well as by the farmer's requirements.
The most useful topography for fish ponds is that which allows the farmer
to fill and drain ponds using gravity.   Ponds built on a slope, for
example, can be drained easily.   If ponds are located on flat land, the
pond must be built with a slope inside it so it can be drained by gravity,
or it will have to be drained using a pump.
Slope.  If the farmer looks at a hillside, he can see that it rises.  It
is higher at one point than at another.   This difference in height, from
high to low point, is the slope of the land.  In more scientific terms,
slope is the relationship between the horizontal distance (length) and
the vertical distance (elevation) over a piece of land.
Slope is usually written as a ratio (1:2) or as a percentage (5%).  A
slope of 1:2 means that for every change in length of 2 meters, there is
a change of 1 meter in height.   A slope of 5% means that for every change
in length of, say, 100cm, there is a change in height of 5cm.  Pond
bottoms usually have a slope of 2-5%, whether they are on level ground
or in a hilly area.  As long as the pond bottom has a slope, it can be
drained completely.
A farmer does not require a scientific understanding of slope to build
a pond.  He does need to know how the shape of his land determines the
best place for building ponds.   Ponds built in hilly places often are
made part of the hill.  The picture on top of the next page, of a pond
with a spring as a water source, shows how the slope of the land has
been used to set up the pond's drainage system.

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In flatter areas, ponds are usually square or rectangular because it is
easier to use a harvesting net in ponds of these shapes.
The farmer will learn quickly to recognize by sight the slope that is
best for a pond.  Because a slope is so important, the first thing a
farmer should look for is a site with a slope and a water supply.  If
he can use a natural slope for his pond, the pond will be cheaper and
easier to construct.
The best places to look for such combinations of slope and water supply
are where water collects from streams and flows through the valley at
the bottom of a slope.  If the pond is built on the slope above the
water flow, water drained from the pond can flow directly into the stream.
Water might be brought to the pond in a number of ways depending upon the
situation -- by streams running down the slope upon which the pond is
situated, for example.  Another good place to look for a good combination
of slope and water supply is on plains or flattish ground between hills.
These plains often receive water from brooks or streams.
There are many possibilities.   The important thing is that the farmer
look for a topography that makes fish farming as easy and as successful
as possible.
The Type of Fish Farm
After the farmer has found a site or sites for his fish pond, he must
consider what kinds of fish culture are possible in the space he has
available.  He also must decide what his resources will allow him to
get started.  This planning is necessary because the answers will
determine the number of fish ponds the farmer builds and the kind of
fish he will want to culture.   The following pages present a range of
ideas concerning the kinds of fish farm operations (raising fish or
breeding fish); the types of pond used in fish culture; fish culture in
one or several ponds; advantages of small and large ponds; and mixing
or separating fish types and sexes.   A discussion of these subjects will
provide the farmer with the background he needs to decide what kind of
fish farm is possible for him, given his resources and the kind of fish he
wants to raise.
A NOTE OF CAUTION  Before a farmer even begins, however, it is important
for him to include in his planning the fact that some fish will die.
This is an extremely important fact for the first-time fish grower to
understand.  It is very natural for some fish, the weaker fish, to die in
ponds.  As long as fish are protected in ponds and are well taken care of,
fewer fish will die in ponds than would die in natural waters.  But a
farmer who does not expect some death may get discouraged and give up
before he has given his pond a chance to work.   It is never too early to
introduce this idea.
KINDS OF FISH FARM OPERATION   In nature, many fish never reach
adult size because they are eaten by other animals (predators), or they
die from disease or lack of oxygen.   In fish culture, the farmer tries
to control the pond situation in order to produce more fish.  In ponds,
predators and so on can be controlled so that the pond yields more fish
per hectare than do natural waters.
There are two major kinds of fish farms -- those which breed fish and
raise the fry, and those which rear fry and fingerlings (the young fish)
to market size.  So the farmer, after finding possible sites, etc., must
decide if he is going to breed his fish and raise the fry.  Or if he is
going to buy fry and fingerlings and rear them to market size, not
getting involved in breeding.
Breeding fish requires more time and more ponds than simply rearing
fingerlings.  And building more ponds can be more expensive and require
more ongoing management.  So the farmer must finally determine his reason
for raising fish:  to eat; to sell; to use his land better; or all of
these.  He will have to have all these things firmly in mind so that he
   *  build the right kinds of pond.
   *   build the right number of ponds.
   *   stock the right kinds of fish.
TYPES OF PONDS  The types of pond a farmer can build depend on water
supply, soil, and topography, the factors which were just discussed.  The
two types of pond most often built are barrage ponds and diversion ponds.
Many aspects of the construction of these ponds are the same.  The main
difference between these two types of pond is the water source.
Barrage Ponds.  These ponds are usually filled by rainfall or by spring
water.  A spring, for example, sends water flowing through a small valley
or down a slope into a low place.   Or a spring bubbles from the ground
into a natural depression.  The pond is formed by collecting water at the
base of the valley and in the low places.   The farmer does this by building
a wall (dam) which holds the water inside what now is the pond area.
The wall keeps the water from entering and leaving except as needed.

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The number of pond walls the farmer must construct depends upon the land
and on how he fixes his drainage system.   A barrage pond usually needs
only one wall -- the main wall between the water source and the pond area.
One kind of drainage system called a sluice (see "Construction" section)
can be used to let water both in and out of the pond.   There are also a
number of simple drainage systems which can be used that do not require
any complicated construction.
Barrage ponds should not be built where the flow of water is too great:
it is difficult to keep the water from breaking down the wall if the
pressure of the water is too great.   Brooks and streams which flow well,
but not too strongly, make good sources for barrage ponds.
Even when the flow of water is not great, however, barrage ponds require
overflow channels.  Because, barrage ponds are usually built in low areas,
they are likely to fill up in heavy rains.   Overflow channels are any
kind of system which can be set up to stop the pond from collecting too
much water.  The overflow takes extra water away from the pond.  If this
extra water is not taken out, the pond wall may break.   Therefore, the
overflow system is needed to help the drainage system handle the flow of
water when there is too much water in the pond.
The overflow system can be wide grooves cut into the top of the wall
toward the ends away from the middle; it can be large hollow tree trunks
which are set into the tops of the wall and work as pipes to drain the
water into ditches, or even to carry the water into storage areas for use
later when the water supply is low.   Another kind of overflow can be
ditches, dug into the ground above pond level, which take the extra water
away when the water rises to that level.
An overflow often is not screened, because if something large catches
on it, the pressure of the water behind it might cause the entire wall to
break.  This fact results in a loss of fish at time of flooding.

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Diversion Ponds.  These ponds are made by bringing (diverting) water from
another source like a stream or river.   Channels are dug to carry the
water from the water source to the pond.

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Diversion ponds can be made in a number of ways.   Sometimes a pond is
dug in flat ground or can be made by slightly enlarging a natural depression
in the land.
These ponds, like the barrage ponds, require walls depending upon the
topography of the land, the drainage system used, etc.   A pond dug in
flat ground often requires four walls; a pond built in a natural depression
may not.
With a diversion pond, the water is always brought to the pond instead
of running directly into the pond.   Water can be diverted in a number
of ways.  For example, a small stream which gets its water from a larger
stream nearby can be dammed and used as a diversion channel to feed a
pond.  Or water can be diverted to a pond from an irrigation ditch which
carries water to agricultural crops from a nearby well or lake.
A farmer may have one diversion pond, or if his space allows and the
water supply is sufficient, he may have several.   When a series of diversion
ponds is built, they are built in one of two ways:
   *   Rosary system.   These ponds are built one after another in a
      string.   In this system, all the ponds drain into each other
      and must be managed as if they were one pond.  Therefore, if
      the first pond in the series (the pond with the water inlet)
      is full of predators which must be poisoned, all the other
      ponds in the system have to be harvested (have the fish taken
      out) and drained before the first pond can be poisoned and

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   *   Parallel system.   In this series, each pond has its own inlet
      and outlet.  Therefore, each pond can be managed as a separate
Each kind of pond is going to have advantages or disadvantages depending
upon the farmer's situation.   A parallel system of diversion ponds, in
most cases, is a better system.   But rosary systems are cheaper and
easier to build, and therefore, more possible for some farmers to undertake.
Also, if the water source is good, and can be kept free of predators
and unwanted fish, and if the management of the pond is done well,
a rosary system can be very successful.
Diversion ponds are often better than barrage ponds because they are less
likely to overflow, and the water source is often more dependable throughout
the year.  But barrage ponds require less construction and are likely
to be cheaper.  In addition, for some farmers, barrage ponds are the best,
and perhaps the only, way for them to use their land for fish ponds.
The art of constructing and planning a fish pond or fish operation is
very much an individual thing.   There are basic ways of using resources,
for example, land and water resources.   But the exact shape and type of
fish pond must be decided by the farmer for his situation.  There are
many ways of making fish ponds which will work, and the "right" way for
any given farmer is the way which works best for him.   Many aspects of
fish farming are determined by experimenting with pond operation, but
much can be done by good planning before fish pond construction.
Therefore, the farmer must look at his sites and consider the types of
ponds he can build from the viewpoint of the number, size, and depth of
the ponds he is going to need.   If, for example, the farmer thinks he
has a good area for a diversion pond, but hits solid rock at 1m and needs
a pond 2m deep, he can find this out before he invests a great deal of
time and money.  If he has room for two small diversion ponds and a
barrage pond, or for a large diversion pond and a barrage pond, he can
base his decision on what kind of pond to build upon the number, size,
and depth of pond he needs for what he will be doing.
The Number of Ponds.  The number of ponds depends on the possible sites
and on what the farmer plans to do with his fish ponds.   If he is going
to raise fingerlings to market size, he will need one or a few "rearing"
ponds.  If a farmer plans a larger operation in which he will breed fish
for the eggs and fry, he will need space for nursery pond, rearing pond,
and a pond for brood stock.  Nursery ponds can hold eggs and fry until
they are fingerling size; rearing ponds hold the fingerlings until they
are market size; brood ponds hold the fish to be used for breeding.
It is possible to breed fish in a corner of a large, single pond, and a
farmer interested in raising fish for his own use may want to do this.
But a farmer interested in marketing fish probably will want at least
two large ponds.  If he has two medium-large ponds, he can use one for
rearing fingerlings and one for broodstock.   Eggs and fry can be taken
care of in very small ponds or even containers.
The Size of Ponds.  The size of ponds depends upon the same factors --
topography, water supply, and need.   Nursery ponds usually are smaller
than rearing ponds because the fry are very small.   The size of nursery
ponds depends on the fish species being cultured.   In fact, eggs and fry
can even be kept in washtubs, oil drums or any other such container which
holds enough water for the number of fry and is supplied with enough

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As the fish grow, they need more space.   So rearing ponds are usually
bigger than nursery ponds, and brood ponds are bigger than rearing ponds.
Sometimes a farmer will have to choose between one large pond or several
smaller ponds.  His site would allow him to decide either way.
Here are some advantages of small and large ponds:
Small Ponds:  *   harvest easily and quickly
              *   drain and refill quickly
              *   treat for disease easily
              *   are not eroded by wind easily
Large Ponds:  *   cost less to build per hectare of water
              *   take up less space per hectare of water
              *  have more oxygen in the water
              *   can be rotated with rice or other crops
For most farmers, a few small ponds are better than one or two large
ponds.  Farmers must also manage their agricultural crops, and it is
difficult for them to manage large ponds.   Also, most farmers just do
not have a lot of land.  A good size for a single fish pond is probably
between 1 and 5 ares (100 and [500m.sup.2]).
Farmers are going to be most interested in working the fish pond into an
already going farm as simply and easily as possible.   This is why
culturing fish in rice paddies is popular in some areas.  In fact, fish
ponds can be set up in almost any area where a rice paddy can be located
-- even on steep hillsides.
Small ponds are easier to care for and construct.   As a farmer gains
experience, he can go on and build larger ponds.   Starting small is a
good idea until the farmer feels he knows what he is doing and is successful.
Depth of Ponds.  The depth of ponds depends upon the fish being grown.
Fish species like different kinds of food, and the depth of the ponds
affects the kinds of food produced by the pond.   A common carp, for
instance, eats worms and other bottom organisms and must have a pond
that is not deeper than 2m.  But when the carp are fry, they eat only
plankton, the tiny free-floating plants and animals suspended throughout
the water.  So nursery ponds for carp fry are often only 0.5m deep.
(As mentioned before, eggs and fry can be taken care of in almost any
container which holds enough water and has enough oxygen.)
Other fish feed at other levels in the ponds depending on their life
stage and on their own food preferences.   A very deep pond will not
produce as much food because the sunlight cannot light the water below
a certain depth, and the plankton will not be able to make oxygen for the
fish (see water quality).  On the other hand, a very shallow pond might
be turbid, covered by water plants easily, and become very hot.  Most
pond owners make sure that the water depth at the edges of the pond is
at least 75cm to discourage water plants.   It is best if the pond is
about 75cm deep at the shallow end and up to 2m deep at the deepest end.
This will give the best results with most pond fish.
THE ONE-POND OPERATION  If the farmer's site can only have one
pond, his decision is easy.  It is hard to breed fish when only one pond
is available.  Usually a single pond is used only for rearing fish from
fry or fingerlings to market size.   This is the case in small, backyard
fish ponds that are used to supply fish for only one family.  A good
minimum size for such a pond is [15m.sup.2] in area and 1m deep.  A smaller
pond would probably not be worth the effort to build and maintain.
A single pond is stocked with the fry or fingerlings.   For example, a
pond of the size mentioned above could be stocked with 60 fingerlings.
These young fish are cared for until they reach adult size.  Then the
pond is harvested (the fish are taken out).   The pond area can then be
prepared for a new batch of fish and stocked again.
One pond can provide a good food source for the family.   However, rearing
fish means that somewhere there must be a source of fry or fingerlings
for use in the pond.  The farmer must check his area carefully, so that
he is sure the young fish are available before he builds one pond.
The source can be a river where he collects the young fish, or a local
fish farm which breeds fish to supply farmers who have small ponds, or a
government hatchery where the farmer can buy the young fish.  If the
farmer decides that he wants to breed fish in his pond, it is possible
to breed some fish inside small nets placed in the pond.  A single pond,
though, is usually used just for rearing fry or fingerlings to a good
size for food and market.
While one pond usually means that the farmer is wise to concentrate on
raising one batch of fish from fry or fingerlings to market size, he
still must decide what kind or kinds of fish he will raise in his pond.
He can raise one kind of fish alone (monoculture), or he can raise
several kinds together (polyculture).

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MONOCULTURE  Monoculture is the culture of only one species (kind) of
fish in a pond.  It can be tilapia of one species, common carp, or any
other single fish species.
Monoculture has some advantages.   One advantage is in intensive fish
culture practices, where fish are fed a lot of supplementary foods for
fast growth.  It is easier to give there foods if there is only one type
of fish in the pond.  Another possible advantage is that monoculture
gives greater control over the age and sex of the fish.   In monocultures,
fish can be of all different ages and life stages, or they can be
separated into fry, fingerlings or brood stock.

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A monoculture allows a farmer who is unfamiliar with fish farming to get
to know his one type of fish very well.   And there is some advantage to

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One disadvantage of a monoculture
pond is that it is more likely
for a single disease or parasite
to kill all fish in the pond.
Different fish are susceptible
to different diseases.  If only
one fish type is present in the
pond, a bad fish disease could
easily infect and kill all the
fish if it were not stopped in

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In monoculture ponds, fish are harvested
selectively by using nets which
have meshes of different sizes.   For
example, if the farmer wishes to
harvest larger fish for market or
breeding, the net will not catch or
hurt the fry or fingerlings, because
they are too small to be caught by
a large-mesh gill net.  This allows
the farmer to keep his pond in
operation and producing fish for
food all year.
Monoculture is the most common kind of pond culture.   For a small fish
farmer who is most interested in having a nearby, year-round supply of
protein (and who does not have a lot of time or interest to give to the
pond), a monoculture may be a very good idea.

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Polyculture is the culture of two or more fish species together in a
pond.  A good polyculture uses the natural food sources in a pond better:
if the polyculture is mixed correctly, each of the species eats a
different food from the pond.

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Polycultures are more
resistant to disease.
Disease, if present,
usually attacks the
smaller, weaker fish,
and the healthier fish
continue to live and
Fish stocked in a polyculture must be able to live together.  And living
together successfully means that the fish put into the pond together do
not all need to eat the same food.   A polyculture can have fish of any
size or age -- as long as a balanced relationship is maintained.
Some examples of polycultures are:
   *   fingerlings of two or more species stocked together in a
      fertilized pond and left to grow.  A good mixture in this
      kind of polyculture is a mixture of Chinese carp -- silver,
      grass, and bighead carp stocked together.  The silver carp
      eats phytoplankton; the grass carp eats pond vegetation;
      the bighead carp eats zooplankton.

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   *   A few large fish (brood size) are stocked with fingerlings
      of another species in a pond and left alone.  A good example
      of this is stocking tilapia fingerlings together with a few
      adult-sized Clarias catfish.  The catfish feed on bottom
      organisms and serve as a population control on the fry that
      are produced in the tilapia ponds.  Since one of the problems
      which can be associated with culturing tilapia is overpopulation,
      this is a very complementary relationship.

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   *   Another example of this type of polyculture is a stocking
      of any kind of fingerlings mixed with a few large grass
      carp for weed control.

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Polyculture is a good way to use a pond, especially if there is only one
pond to use.  A careful examination of local fish and their habits should
tell a farmer what kinds of polycultures are possible in his pond.  The
important thing to remember is that the fish must not compete with each
other.  If stocked and managed correctly, polyculture ponds can give
maximum production to a fish farmer.   In very practical terms, the farmer
could raise as much as three times more fish in a polyculture of three
species than he can raise in a monoculture pond of the same size.
MONOSEX CULTURE  A word should be said about monosex culture, even
though few farmers will choose or be able to choose this way of operation.
Monosex culture means growing only one sex of one species of fish in a
pond.  When only males or only females are stocked in a pond, all the
energy of a fish goes into growth and not into reproduction.
An all-male stocking has faster growth rates than a mixed stock of males
and females.  So some farmers try to stock only males or females in a
pond.  One fish species that often is used in monosex culture is tilapia.
Tilapia reproduce at a very small size, but when separated by sex, they
do not develop their reproductive organs, yet continue to grow.
One way to stock a monosex pond is to separate the fish one by one
according to sex during the breeding season.   Often, at this time, fish
change color, and it is easier to sort fish by sex.   Then the fish can
be grown to a larger size.
In another method, people have been trying to obtain fish of all one sex
by putting two different species of tilapia into a pond.  When these fish
breed, they produce either a monosex culture or a sterile hybrid.  Three
crosses do now produce 100% male offspring.
Crosses of Tilapia which Produce 100% Male Offspring:
MALE                         CROSSED WITH   FEMALE
Tilapia macrochir                  X        Tilapia nilotica
Tilapia mossambica                  X        Tilapia nilotica
Tilapia hororum                     X        Tilapia mossambica
There are no crosses that produce 100% female offspring as yet.  Males
are preferred because they continue to grow during the breeding season,
when there are no females present -- even though they (the males) continue
to build their nests in preparation for mating.
Monosex culture is a valuable method of pond culture, but is usually
difficult to do:  the hybrid crosses are very new; hand-sorting fish by
sex causes many of the fish to die from stress.   Even if the fish are
sorted without stressing them, one fish of the opposite sex that
accidentally finds its way into the pond can ruin the whole monosex
culture.  So monosex culture is generally not practiced by small-scale
fish farmers.
THE MORE-THAN-ONE-POND OPERATION   A farmer who has a larger
area to work with might wish to consider having two or three small ponds.
Perhaps two ponds would be diversion ponds, and the third a barrage
pond fed by a spring.  Perhaps the farmer has room for only two barrage
ponds.  He does not want to keep eggs and fry in the ponds because it is
harder to protect eggs and fry in barrage ponds.   This does not mean he
cannot breed fish.  He can keep eggs and fry in an oil drum, washtub,
or anything else as long as the water is clean and contains plenty of
With three ponds, one pond can be the rearing pond in which fingerlings
are raised to market size; one can be used to keep brood stock; and the
third, and perhaps the smallest, can be used as a nursery pond where the
eggs hatch and the fry grow to fingerling size.   If the farmer does not
plan to breed fish, then he can use all three ponds as rearing ponds.
He should not do this, however, without thinking ahead to the harvest
and making plans for marketing the fish he will grow, or preserving the
fish for sale or use later.

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The major difference between a large farm operation and a small one may
be only the number of ponds.   Three ponds is enough to have a full-fledged
operating fish farm which includes breeding, selling fry and fingerlings
to other farmers, and raising fry and fingerlings to market and brood
size.  Once the farmer is a skilled pond manager, these ponds should do
well and provide a good return on his investment.
Until the farmer is experienced, however, it is better for him to start
with small efforts and a smaller operation.   Small pond failure is not as
severe.  Once the ponds are working well, the farmer can expand and build
more and/or larger ponds.  But he should be encouraged to start small.
There are a lot of factors in fish pond management that are learned best
by experience.  But a bad experience will discourage, rather than encourage,
the pond owner.
A FINAL WORD ON PLANNING PONDS   Good planning is a must for a
successful fish pond operation.   It is during the planning process,
before any money or a lot of time and energy is spent, that many problems
can be solved.
The farmer should keep in mind while planning that ponds do not have to
have expensive equipment in order to work well.   Far more important than
the equipment are 1)  an understanding of the general principles involved,
2)  the selection of a fish or fishes that will do well in his pond (see
next section, "Selection of Fish"), and 3) good daily management of the
pond (see section 6, "Managing the Pond").
3           Planning:  Selection of Fish
The farmer now has a firm idea of his site and the types of ponds it is
possible for him to build.  He also should know what he wants to do with
his ponds -- raise fish for food or run a fish-marketing business.  Now
he must consider very carefully what type or types of fish he is going
to raise in his ponds.  The success of the pond depends upon choosing
the fish that will grow best in the type of ponds and conditions that a
farmer is planning.
The following pages give some:   1)  general information on characteristics
of fish, and 2)  detail about certain fish which have proved to be good
pond fish and why.  This information should serve as a guide to a farmer
trying to decide which fish will do best in his ponds.
Characteristics of Fish
The major body parts of all fish perform the same functions, and they
are located in about the same places on any different fish's body.  But
the size, shape, and color are often different, and these differences
help tell the fish apart.  Knowing how a healthy fish looks is important.
All fish have a tail consisting of the caudal peduncle and the caudal
fin.  The fish's fins help it steer through the water and hold it
upright in the water.  Often a sick fish cannot steer or flops over on
its side.  Other fins on the body include:
   *   Pectoral -- usually located on the sides of the fish behind
      the head.
   *   Pelvic -- usually located towards the rear of the body where
      the hips would be if the fish were a four-legged animal.
   *   Dorsal -- runs along the top of the fish.  May be single or
      double.   The second dorsal fin is sometimes called the soft dorsal

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   *   Anal -- usually located right behind the aral vent (anus) on
      the rear bottom end of the fish.
Most fish have eyes, but even with eyes fish cannot see very well.
All fish have gills.  The gills are covered by a flap called the
Operculum.  The gills are extremely important.  Fish take in water
through their mouths.  The water is then passed through the gills
which remove the oxygen and nutrients from the water.   The water
is then passed outside of the body of the fish through the gill slits.
It is possible to tell a lot about a fish's health and eating habits by
looking at its gills.  Fish with many, many feathery gill rakers and
few if any teeth eat the smaller foods in the pond.   Fish with few and
larger gill filaments eat the larger particles from the pond.  Healthy
gills are a bright red color.   If the farmer sees fish with gills that
do not have this healthy red color, or have white spots all over, for
example, he will know that fish is not healthy and should not be bought
or placed in his pond.  Or if the fish is already in his pond, he knows
he must take steps to get rid of the disease before it troubles more fish.
Other identifying parts that all fish have are the mouth, the genital
openings (to reproductive organs), and the lateral line.  The lateral line
is a small line of nerve cells which runs along the length of the body
about midway on the side of the body.   Sometimes the lateral line is
covered by a layer of scales; sometimes it is a different color than the
rest of the body.  In any case, the lateral line is an area of sensitivity
that helps the fish feel pressure and temperature changes in the water
around it.
Some fish, like catfish, also have barbels, small projections that hang
down from the sides of the mouth.   Barbels help the catfish sense its
surroundings, find food, and attract small fish to the catfish so that
it can eat them.

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When a farmer breeds fish he will want to be able to tell the difference
between male and female fish.   This can be difficult with some fish.
However, some fish change color in the breeding season (tilapia, for
example), so they are easy to identify by sex.   Some fish can be classified
according to the color and size of their genitals.   The separation
of fish by sex is best learned by actual experience in the pond.

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When the farmer goes to buy fish, he must already know what healthy fish
look like.  It is very important that he be as familiar as possible with
each of the fish he decides to raise.   He must know the characteristics
of that fish and its life cycle, its eating and breeding habits, etc.
The farmer who begins any fish pond enterprise without having this kind
of information is inviting failure.   And if it is a new venture, it is
particularly important that the farmer's first effort be as successful
as possible.
The Life Cycle of Fish
Fish start life as fertilized eggs.   The eggs grow and then hatch into
small fish, called fry.  The fry are attached to the yolk sac which is
the leftover part of the egg they hatched from.   The yolk sac provides
food for the fry during the first few days after hatching.

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After the yolk sac is gone, the fry searches for food in the water.  All
fry eat the tiny suspended and swimming plants and animals called plankton
in the water.  Plankton are hard to see, but if a farmer puts some
of his pond water into a glass container and holds it up to the light so
that the light shines through the water, he can see the tiny plankton
floating in the water.  The length of the fry stage depends upon the
species of fish.  Usually a fish is a fry at least until the yolk sac is
absorbed.  Fry range from 2mm to 30mm in length.  This growth process can
take 2 to 6 or 8 days depending upon the type of fish.
As the fry grow bigger, they are called fingerlings.   They are called
fingerlings because at this stage of the growth cycle, they are about the
size of a person's finger.  Fingerlings vary in size -- from 4-1Ocm.
Above 10cm, the fish is better called a post-fingerling.  The adult fish
ranges in size; some can be as large as 2m long and weigh 22kg.  An adult
fish is a fish which is sexually mature.
Fingerlings have different eating habits from fry; they are now much
bigger and can eat larger pieces of food.   As fingerlings, the fish begin
to show that they like certain foods better than other foods.  Each kind
of fish chooses its own kind of food, depending upon his needs and what
is available.  For example, a carp fry will eat plankton; as a fingerling,
the carp eats pieces of decayed matter and insect larvae; as an adult
the carp will eat plankton, decayed matter, insect larvae, worms, snails,
and almost anything that is on the bottom of the pond.   Common carp, for
example, are called "bottom feeders," because they eat food from the bottom
of the pond.

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The food preference does not always
change as the fish grows.  Some fish,
like the silver carp, eat plankton
their whole lives.  When the fish
reach adult size, they will sexually
mature in the right conditions.
Brood fish are sexually mature fish
which are chosen as good fish to
breed (spawn), produce eggs and
begin the whole cycle again.   This
is called the life cycle of a fish.
Knowing how the fish in the pond
grow, and the foods they require at
each stage in the life cycle, is very
important for good pond management.
Choosing Pond Fish
Choosing fish to grow in ponds can be difficult.   A good pond fish has
certain characteristics which help it grow successfully in ponds.  There
are some fish which will not adapt to pond conditions and cannot be used
in pond culture.  A pond is very different from a natural waterway:
   *   There is usually no water flowing through a pond.  Some fish
      need to live where there is quite a bit of current in the
      water, rather than in a quiet pool of water.
   *   The food that is already in the pond is all that is available
      to the fish, unless extra food is put in by the farmer.   
   *   There is only a certain amount of water and pond area in which
      to move about.
There are many fish that do grow well in ponds.   Some of these are fish
grown locally; some are fish grown in other parts of the world.
Many governments today are introducing exotic fish species (these are
kinds of fish not native to that country) into fish pond programs.
They do this for three reasons:
   *   Some  Introduced fish grow better and faster than native fish.
   *   Some introduced fish are preferred by people for eating (over
      local fish).
   *   The offspring of a cross between a local fish and an introduced
      fish sometimes grow faster and taste better than either of the
      parent fish (this is called hybrid vigor).
But exotic fish must be watched and used very carefully.  They must not
escape into local waters.  Some exotic fish which escape create problems
in natural waters when they begin to compete with local fishes for food.
Also, introduced fish can carry diseases or parasites that are fatal to
native fishes.
There are certainly a number of fish in the natural waterways of your
area which will grow well in ponds.   Native (local) fish are usually
easier to use because they are adjusted to local water and climate
If at all possible, farmers should be encouraged to start their ponds
using a tested pond fish which is locally available and is well-liked
by people in the area.  It can be a fish from the list given here or
one chosen from a list prepared in your area.   The important points
are that the farmer be able to sell any fish he wishes to sell, that
the fish can grow in ponds, and that there is brood stock available
Fish Used in Pond Culture
Here are some characteristics that good fish for pond culture will have.
Certainly it may not be possible for a farmer to determine whether a
certain fish has all these characteristics right away, particularly for
those local fish not discussed in detail here or those newly introduced
to pond culture.  But good pond fish all have certain characteristics:
the more certain a farmer can be that the fish he chooses to raise fit
these descriptions, the more sure he can be of his success.  Good pond
fish are:
   *   available locally
   *  able to reproduce (breed) naturally in your area.
   *   able to live in a confined space (the pond).
   *   able to find the right foods in ponds.
   *   fast-growing.
   *   relatively free of parasites and diseases.
   *   known and liked as a food fish in the area.
Some fish that fit these criteria for good pond fish and are now grown
in ponds all over the world are named here.   Though they all are grown
in ponds, each has certain characteristics which mean that it will grow
better in some kinds of ponds better than other ponds.   Of course, these
fish are not the only fish that can be used in ponds.   But they are named
here because they have been tested in ponds, and they can grow well under
pond conditions.  All of these fish are warm water fish.
     Please note:  Each fish has a scientific name which is
     always the same.  The common name, however, can be different
     from one country to the next.  It is a good idea for anyone
     who works with fish to know the scientific name.
     Genus - species                                  Common name
 1.   Anguilla japonica                                 eel
 2.   Aristichthys nobilis                              bighead carp
 3.   Barbus gonionotus                                 tawes
 4.   Carassius auratus                                 goldfish
 5.   Carassius carassius                               crucian carp
 6.   Catla catla                                       catla
 7.   Chanos chanos                                     milkfish
 8.   Cirrhina molitorella                              mud carp
 9.   Cirrhina mrigala                                  mrigal
10.  Clarias batrachus                                catfish
11.  Clarias macrocephalus                            catfish
12.  Ctenopharyngodon idellus                         grass carp
13.  Cyprinus carpio                                  common carp
14.  Helostoma temmincki                              kissing gourami
15.  Heterotis niloticus                                 -
16.  Hypophthalmichthys molitrix                       silver carp
17.  Labeo rohita                                     rohu
18.  Mugil cephalus                                   mullet
19.  Mylopharyngodon piceus                           black carp
20.  Osphronemus goramy                               gourami
21.  Serranochromis robustus                             -
22.  Tilapia macrochir                                tilapia
23.  Tilapia melanopleura                             tilapia
24.  Tilapia mossambica                               tilapia
25.  Tilapia nilotica                                 tilapia
26.  Trichogaster pectoralis                          snakeskin gourami
27.  Trichogaster trichopterus                        three-spot gourami
Following is specific information on some of the more popular pond fish.
The common carp, Cyprinus carpio, is a favorite warm water pond fish.
Common carp are used as a pond fish because they:
   *   spawn easily in ponds.
   *   do not get sick easily.
   *   tolerate wide ranges of temperature and pH (factors of water
      quality discussed in detail later).
   *   eat all kinds of food, from zooplankton to decaying plants.
   *   have a very good growth rate.
   *   accept supplementary foods.

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Common carp generally are a grey-green color.   However, they also can be
gold, yellow, orange, pink, blue, green, or grey.   They spawn all year
round in warm waters, and they can be made to spawn by the pond owner if
they do not spawn naturally.   Common carp are good to eat when they are
cooked properly.  They can be grown in ponds by themselves (monoculture)
or in ponds with Chinese or Indian carp (polyculture).
Some of the yields gotten in various countries by stocking common carp in
monocultures are shown in the following table.
Country                 Culture methods                    kg/hectare
Czechoslovakia          Growth in ponds with ducks               500
Guatemala               Intensive culture in ponds             4,000
India                   Natural growth in ponds                  400
                        Growth in ponds with management        1,500
Indonesia               Intensive culture in ponds             1,500
Japan                   Intensive culture in ponds             5,000
Nigeria                 Commercial culture with
                          fertilization and feeding         371-1,834
Philippines             Intensive culture in stagnant water     5,500
United States           Intensive pond culture with
                          inorganic fertilization                 314
     Source:   Bardach, et al (1972)
Conclusion:  Common carp are a very easy fish to breed, keep, and harvest,
so a fish pond that relies on common carp will probably do well.  Common
carp are a good fish for a farmer to use for his first effort.  With good
management, common carp will continue to produce healthy eggs and fry
until they are too old (above 5 years of age).
The Tilapia genus (family Cichlidae) contains at least 14 species, which
are all good pond fish.  The color of the fish differs only slightly
depending upon species; tilapia are generally dark brown to black in
color.  The most common species grown in ponds is the Tilapia mossambica,
also called the Java tilapia.   It has been introduced throughout the world
and is easy to find in most places.   Tilapia:
   *   are hardy fish, resistant to disease.
   *   breed easily in ponds.
   *   grow rapidly.
   *   taste good.
   *   can withstand wide temperature ranges.

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Tilapia are herbivorous:  some species eat higher plants; some eat
phytoplankton.  Both the Java tilapia and the Nile tilapia (Tilapia
nilotica) do well in very enriched waters (waters polluted by sewage).
All tilapia have slightly different eating habits, depending on the
Tilapia reproduce every month or so, once they become sexually mature.
They then take very good care of their own eggs and fry in ponds.  If
the farmer plans to breed and raise fry, this fish is a good choice
because the fish themselves take care of the fry at a stage where many
fish of other species die easily.   The major problem with raising tilapia
in fish ponds is that they become sexually mature at a small size, and
begin to reproduce instead of to grow further.   It may be necessary to
separate the tilapia by sex before they are old enough to reproduce.  Or
it may be necessary to introduce catfish into the pond to control the
population of small fish.
Conclusion:  Tilapia species have many possibilities for pond culture.
Their fast growth rate, ease of breeding, good taste and hardy bodies
make them a good choice, particularly for the first-time fish farmer.
Other kinds of carp, besides the common carp, often are grown in ponds.
Most commonly used are the Chinese carps.   Some of these are:

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   *   Silver carp (Hypophthalmichthys molitrix).  This fish eats
      phytoplankton, but will accept rice bran and bread crumbs. 
      The silver carp gets its name from its silver color.  It has
      very small scales.

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   *   Bighead carp (Aristichthys nobilis).   This fish feeds mainly
      on zooplankton.  It is a dusky green color on top which fades
      to a pale green color on the abdomen.  It also has small scales.

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   *   Grass carp (Ctenopharyngodon idellus).   This fish is an
      herbivore and eats water vegetation (but also will eat
      almost anything).  The grass carp is also silver-colored,
      but has a darker grey area running along the top of the body.
      It grows larger in size and has larger scales than a silver
Other chinese carps like the black carp (Mylopharyngodon piceus) and the
mud carp (Cirrhina molitorella) are bottom feeders.   This difference in
eating habits is very important in fish pond culture.   It is the reason
why polyculture, or growing a number of fish species in one pond can be
successful.  When one kind of fish is stocked alone in a monoculture,
the foods in the water not eaten by that type of fish are wasted.  In a
polyculture of the above three species of Chinese carp, for example,
three kinds of food are being eaten.
The following table gives some examples of polyculture mixes and of how
many fish of each kind can be stocked in a pond.   For example, Pond I is
stocked with silver, bighead, grass and common carp.
                Weight of             Number of Yearlings per hectare
Species         Yearlings, grams
                                        I             II          III         IV
Silver and
  bighead carp         500              4,500        4,500       9,000        9,000
Grass carp            500               600           -          3,000
Black carp            500               -             450                    3,000
Common carp           200               200           200          200         200
  TOTAL:                               5,300         5,150       12,200      12,200
      Source:  Bardach, et al (1972)
The preceding table shows polyculture mixes:   as you can see, common carp
can also he used in polyculture with Chinese carp.   Chinese carp are
grown in ponds because they grow well in polycultures, and they are very
good to eat.  The silver carp grows faster and is tastier (according to
some farmers) than common carp.   The grass carp is most often used to
control weeds in the pond.  In fact the grass carp does a better job of
weed control than do chemicals.   The grass carp is perhaps the most interesting
of the Chinese carp and is now being studied by scientists in
many countries to find better ways of breeding it in ponds.
A farmer might run into problems raising Chinese carp -- if he does not
look into his local situation very well.   Farmers will have to have a
source of Chinese carp fry from a government hatchery or a local breeder
before trying to raise Chinese carp.   The carp only breed once a year,
and then, in most cases, only with help from man.   Also, Chinese carp are
very susceptible to diseases.   Then, because they are delicate fish, they
must be handled very carefully, or they will be injured.
Conclusion:  A farmer just beginning a fish pond probably would not want
to breed Chinese carp, but he certainly should be familiar with these
fish and how they might help his ponds.   For example, even two or three
large grass carps placed in a pond with many fish of one other species,
could be valuable for keeping a pond balanced.
There is one last group of carp often cultured in ponds.  These are the
Indian carp.  Indian carp are further divided into minor and major carp.
The major carp of India are the catla (Catla catla), the rohu (Labeo rohita),
and the mrigal (Cirrhina mrigala).   The minor carp are the reba, the bata,
the sandkohl, and the nagendram fish.   The Indian major carp will not
spawn in standing water, so special ponds are built in India to provide
a flow of water for these fish, who must have running water in which to
spawn.  The Indian carp can be made to spawn by man, but this is a difficult
process (see "Managing Brood Stock").   However, there seems to be
no reason why the Indian carp cannot be spawned in ponds in places where
ponds can be constructed to provide constantly running water.

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Conclusion:  A farmer who has only a small pond should not try to breed
Indian carp.  Indian carp can be grown in polycultures with common carp,
but are not as good or fast growing in ponds as the Chinese carp.
Indian carp are also susceptible to many diseases.   This is a fish for
an experienced fish farmer who is interested in, and able to, experiment.
The gourami (Osphronemus goramy) is a very good pond fish.  It is
originally from Indonesia, but now is grown all over Southeast Asia.
Gourami possess an accessory air-breathing organ, which means that they
can survive in waters that are low in dissolved oxygen.   This makes it'
an important fish in areas where the temperature remains high and there
is little water for certain periods of the year.   Gourami spawn all year
round in warm water conditions.   Gourami:
   *   spawn easily all year round in warm waters.
   *   taste good.
   *   are easy to breed.
   *   accept a variety of foods.
   *   are hardy.

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Conclusion:  Gourami are good fish for a first-time fish farmer.  And
they are certainly a fish to be considered very thoughtfully by farmers
who live in areas that remain very hot and dry for periods of the year.
The gourami is used to these conditions, and there are other pond fish
which would not do well at all under these conditions.
Clarias catfish are found throughout Asia, India, and Africa, as well as
the Middle East.  The species most often used as pond fish are Clarias
macrocephalus and Clarias batrachus.   Clarias macrocephalus is preferred
for its good taste; Clarias batrachus grows faster.

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These catfish have accessory air-breathing organs; they can even crawl
out of ponds to look for food.   Because they can live in shallow ponds,
these catfish are sometimes used in culture with rice (see paddy culture).
They are scavengers, which means they will eat just about anything.
However, they prefer to eat worms, snails, and other fish.  They are
often used in polycultures with tilapia where they serve as predators on
the very small tilapia.  They will eat supplementary foods, and give very
high production in ponds.  In Thailand, Clarias catfish yield about
97,000kg/ha when they are fed supplementary foods.   These catfish are
hardy:  they sometimes get external parasites, but these do not kill the
Conclusion:  The catfish are another good fish to be raised in areas
where high heat and long dry spells are found.   They are good to eat,
easy to keep, and can be used in ponds in a number of ways.  Certainly
a farmer who already cultures paddy rice might be interested in considering
adapting his paddy to catfish culture.
The common name tawes is applied to three species of fish -- Barbus
gonionotus, Puntius javanicus, and Puntuis gonionotus.   These fish
usually are used in fish ponds for vegetation control, in polycultures
with Chinese carp.  Tawes are able to spawn all year round, but they
most often spawn in the rainy season.   Tawes need well-oxygenated water
with a strong current to spawn.   Tawes feed on soft water plants, but will
also take rice bran.  There is not a great deal known about the tawes at
present, but it can be used in polycultures when the grass carp is not

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Conclusion:  A farmer starting a polyculture certainly might be interested,
in using this fish.  However, first-time fish farmers with limited space
would not want to try breeding this fish.
The Heterotis niloticus spawn easily in ponds.   The mature fish will
build a grass-walled nest in the weeds at a pond's edge and spawn inside
this nest.  They spawn when water is low and very warm, at the end of
the dry season.  The mature fish feed only on plankton, but in a pond
they will accept supplementary food.   This fish has a swim bladder which
can serve as an accessory air breathing organ.

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Conclusion:  There is not yet a great deal known about the Heterotis
niloticus as a pond fish.  But it seems that it is a good choice of fish
for warm climates and warm waters.   A farmer who lives in such a climate
might find raising, and even breeding, this fish quite easy -- particularly
in a very well-fertilized pond.
These are the snakeskin gourami (or Sepat Siam -- Trichogaster pectoralis),
the three-spot gourami (Trichogaster trichopterus), and the kissing
gourami (Helostoma temmincki).   All of these fish taste good.  And they
breed easily in well-oxygenated, warm water.   They do require a pond which
has a good growth of vegetation (particularly Hydrilla verticillata).

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Conclusion:  In a pond situation such as that outlined above, these
gouramis are easy to breed and raise.   They are a good fish to use in
polycultures with other gouramis, tilapia, and common carp.
The milkfish (Chanos chanos) can be raised in freshwater even though it
is primarily a brackishwater fish, and will not breed in ponds.  The fry
are caught along the shoreline at breeding season (the rainy season) and
transferred to freshwater ponds.   Milkfish culture is done for the most
part in the Philippines and in some other Southeast Asian countries, like
Indonesia and Taiwan.
Adjusting (acclimatizing) the fry from the saltwater to the freshwater
pond is hard to do; many fish die if the adjusting process is not done
well.  Therefore, milkfish usually are cultured in brackishwater ponds
only; the use of milkfish in freshwater ponds is not widespread.  Milkfish
feed on a complex of bottom algae, and, recently, it is reported
they also feed on phytoplankton.   Milkfish are prized for their beauty
and their good taste, though they have many, many small bones.

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Conclusion:  This is not a fish for the first-time fish farmer.  In fact,
it is not a good choice for any farmer unless he has a saltwater pond; is
interested in trying to acclimatize the fish to a freshwater pond; or can
buy milkfish from a source that has them already in a freshwater pond.
Eels (Anguilla sp.) have been cultured in Japan and Taiwan for years.
Eels are very much a luxury food and are not normally grown alone in ponds
outside of these two countries.   The eels are grown in ponds in polyculture
with other fishes and are particularly useful in polyculture
with species of tilapia because they eat the smaller tilapias.  The eels
used in Taiwan (Anguilla japonica) spawn in the sea and the fry (called
elvers) swim upstream and are collected by dealers.   Eels must be fed
supplementary feeds like pellets made of trash fish.
Conclusion:  It is not recommended that farmers work with eels because
they must be fed protein and are not very efficient converters of food.
Also, eels cannot be bred in fish ponds.

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Some other fish grown in ponds are the goldfish (Carassius auratus), the
crucian carp (Carassius carassius), and Serranochromis robustus.  Any   of
these fish can be grown in polycultures with Chinese, common carp, and
Conclusion:  The use of one of these fish in a pond stocked with other,
more important fishes, results in an increase in yields of both species.
In polycultures these species can utilize other food sources and also
act as predators and weed controllers.

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One other fish species used in freshwater ponds is the striped mullet
(Mugil cephalus).  Like the milkfish, the mullet is primarily a saltwater
fish, and its fry are collected as they swim upstream.   Recently the
mullet has been made to spawn by man, but this is difficult to do because
mullet are very sensitive to handling.   However, mullet can survive in
wide temperature ranges and are herbivores, so some farmers may want to
try mullet.
All these fish have been and are now being cultured in fish ponds around
the world.  However, as stated before, they are not the only fish which
can be grown in ponds.  In every area there are a number of fish in
natural waters that could be grown in fish ponds.   So you might find it
a good idea to experiment with local fish in your ponds, to find those
fishes that might be available to farmers in your area for use in their
ponds.  It is better for an extension worker to do the experimenting
than it is to have a farmer risk wasting his time or money, or even more
importantly, risk failure.  If a farmer fails, he may not want to try
4           Fish Pond Construction
Construction of a large pond can be very expensive if labor is hired,
machines are used, and expensive equipment is rented.   For example, in
the Philippines, a one-hectare pond having two concrete gates and walls
3m high x 3m wide recently cost US$1,522.56.   Another pond, about 100m
x 25m, with only a Rivaldi valve cost about US$680.
An interesting fact about fish pond construction is that whether the
pond is large or small, expensive or inexpensive, ponds are all very
much the same.  A larger, more expensive pond will not necessarily be
a better pond.
Here is an example of a good beginning for a new and small fish farmer:
     A "backyard" fish pond was planned and sited very carefully
     by a farmer.   The pond was dug by the farmer and constructed
     with bamboo pipes for water inlets and outlets.  The construction
     itself cost no money.  The farmer's only expense was a
     supply of fingerlings purchased from a nearby market.  This
     fish pond, managed by the farmer and his family, produced
     enough fish for the family and some extra income from fish
     sold or bartered for goods needed by the farmer.  The family
     ate well and suffered no major illnesses during the year.
     Next year, the farmer plans to add another pond and to produce
     more fish for market.  He will add a Rivaldi valve or a wooden
     monk to this new pond, because either of these will make ongoing
     management somewhat easier, now that there will be two
     ponds to manage (The bamboo pipe sometimes got clogged.  This
     was no problemn to correct when there was only one pond.  But
     it would take up needed time in a two-pond operation).
     Whichever the farmer chooses, the valve or the monk, he will
     make it himself with materials found locally, using money from
     the sale of his fish.
     This farmer began his operation well.  He started small and
     worked into a larger operation.  However, even for the larger
     fish farm, he planned an expansion which was within his means.
     This kind of careful planning increases the farmer's chances of
     success -- and yours.  And the scope of the project is something
     he can undertake on his own.  He gained the knowledge and
     experience that he needs to expand his operation.
The following section presents a range of ideas for constructing fish
ponds.  The farmer can pick a combination of construction possibilities
which best fit his own needs and resources.
IMPORTANT:  Stress that the "right" way in any situation is the way
   *   the owner can afford
   *   the owner can manage easily
   *   fits the owner's needs most completely
Construction should begin only after careful planning such as that
outlined in the preceding sections on "Planning."

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A fish pond has three main parts:   the walls, the water inlet, and the
drainage system.  Walls are also called dams, dikes, levees, or bunds.
This manual uses "walls."   Whatever they are called, walls hold the water
in the pond.  They can be built using soil taken from inside the pond,
or they can be built with soil taken from another place.  They must be
strong enough to withstand the pressure of all the water inside the pond:
water constantly pushes against the walls.   They must also be water-tight
(impermeable), so the pond does not leak.
The water inlet, located above the pond water level, is used to let water
into the pond and is closed off after the pond is filled.
The drainage system is used to empty the water from the pond when the
farmer is ready to harvest the fish.
There are many ways of making inlet and drainage systems:  the most
important criterion is that they work.   But the walls are especially
important:  they are all that keep the fish inside the pond.  The walls
must be built carefully.
Pond construction follows the same principles whether the pond is a
single backyard pond or part of a large fish hatchery.   These are the
steps in pond construction:
   *   Survey the land
   *   Mark out the area of the pond
   *   Measure and mark out the walls
   *   Excavate the pond bottom, if necessary
   *   Build the drainage system
   *   Build the water inlet
   *   Build the walls
   *   Seal the pond bottom and walls
Each  of these steps will be discussed in detail in the following pages.
Survey the Land
The first step in the construction of a fish pond is marking the area of
the proposed pond.  If the site chosen is a natural slope, the first
thing to be done is to find out where the main wall will be built.  The
main wall should be marked off at the lower end of the pond, where the
pond will be the deepest and the slope the greatest.   This is where the
pond's drainage system will be put.   If the pond is to be on a flat area,
the pond bottom itself must be made with a slope so the pond will drain.
This is done by digging one end deeper than the other end.  Remember:
the main wall is always at the deeper end.
Even flat ground usually has some kind of slope, although it may be very
little and hard to see.  So, before constructing the pond, the land is
surveyed to find out which way the land slopes and what that slope is.
There are a number of ways which can be used to determine slope.  The
way outlined here probably would not be used by many farmers if they
were building a pond on their own, but this is an accurate method of
determining slope and should be encouraged if at all possible.

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To survey the land for slope, some
stakes (long, straight pieces of
wood), some string (fishline, etc.),
and a carpenter's level are needed.
Most farmers will not be familiar
with the level, a device that has
an air bubble trapped inside which
rests between two drawn lines.
When the level is placed on the
ground, it shows whether the area
is flat or sloped:  if it is straight
or flat (level), the bubble stays
in the middle between the lines;
if the land slopes, the bubble will
move to the right or left of the
lines, depending upon the direction
of the slope.

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Farmers who cannot find a carpenter's
level can make a level by getting a
small lightweight container.   They
should then place the container on a
known horizontal surface, add water,
and draw a line around the inside of
the container at the water level.
Then, if this container is placed on
a slope, the water will shift away
from the line to show the slope.

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When all the equipment is gathered, measure the slope.
   *   Look at the land and decide which part is higher.
   *   Drive a stake or a piece of wood or bamboo into the ground
      at the highest point.
   *   Walk away downhill from the stake about 100cm.  Drive another
      stake into the ground at this point.
   *   Tie string or fishline or vine (whatever is being used)
      between the two stakes.  Attach the level to the string.
      Then move the string up and down on the stakes until the
      bubble is between the lines on the level, or the water
      level is even with the line marked on the container.
       This will mean the string is level between the stakes,
      even though the stakes are in the ground at different
   *   Measure the height of each string by measuring from ground
      level to the place where the string is tied.

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This drawing shows that one string is tied at 20cm; the other is tied at
25cm.  Therefore, one end of the area is 5cm lower than the other.  The
distance covered by the string is 100cm, so the slope is 5% (over 100cm
of ground, the elevation changed 5cm).   Since a slope of 2-5% is good for
a fish pond, this site has a satisfactory slope for a pond.
Other Ways of Determining Slope.   As mentioned earlier, the above method
of measuring slope is a good one, but it my be difficult for some people
to do.  It is possible to calculate slope roughly.  A farmer, who realizes
that what he is looking for is a way to place his pond so that the water
can enter from the water source and drain away well, can figure the slope
of his land by doing such things as rolling a ball or other round object
and watching carefully to note where and how quickly the ball rolls.  A
good slope would mean a slow-rolling ball.   A variation of this involves
throwing a quantity of water, or a mixture of water and dye, on the ground
and watching the path it takes and its speed as it moves along the ground.
It is important to consider slope carefully.   A well-placed pond with
good drainage is easier to care for and has more chance to be successful.
It may be necessary for the pond owner to measure his land only once to
find a good location.  Or it may be necessary to repeat the measuring a
number of times.  This is probably a good thing to encourage since
locations which look alike to the eye often have enough difference in
slope to make a big difference to a fish pond.   Also, determining slope
is a larger project if more than one pond is being built.  Then the Ponds
must be laid out in relation to each other.
There may be several areas which have the correct slope, but only one
which is good in terms of getting the water into the pond from the water
source and out of the pond easily.   For example, the farmer might like
to drain his pond so that the water irrigates his fields.  Therefore, he
will want to keep this in mind when he decides upon the exact placement
of his pond.  Likewise, if he is building a pond on a hillside in back
of his house, the slope may be perfect, but he will need to avoid drainage
into his buildings.
Once the slope is found, the location of the main wall can be determined.
Of course, if the pond is built on flat ground, it will have four walls.
If the pond is a barrage pond, it may only have one wall.  The number of
walls depends upon the land.   The shape of the land may mean that one
wall or two walls or four walls will be needed.
Mark out the Pond Site;
Measure, the Walls
Now that the slope is known, the place of the main wall is known.  The
main wall is at the end of the pond which will be deepest, and is the
wall where the drainage system will go.
Mark out the main wall, and any other walls that will be built, with
stakes.  The walls, when finished, will be wide:  it does not matter so
much where the stakes are placed within the width of the planned walls,
for they are to be used as height markers.

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The farmer has to plan the depth of his pond and the height of his wall.
If the pond is going to be 2m deep at the deepest end, for example, the
walls should always be at least 30cm higher than the water level for a
small pond, and at least 50cm higher for a large pond.   Also, the walls
will settle after they are finished, so it is best to make the wall 10%
higher than the desired final height of the wall.   A 2m deep pond, therefore,
would have walls with a total height at the deepest point of 2.5 or
2.6m [height of wall before it settles = depth of pond + 30cm (for small
pond) or 50cm (for large pond) + 10% of depth and 30 or 50cm].
Tie strings to the stakes along the main wall line, at a height of 2.5
or 2.6m for a pond whose deepest end will be 2m.   Use a levelling device
to connect strings to the stakes marking the other walls, if the pond has
other walls, at the same level as the string marking the height of the
main wall.  The strings are the building markers.  When the walls reach
the strings, they are the right height.
Dig the Pond Bottom
As stated before, the pond bottom must slope downward from the shallow
end to the deep end to help drainage.   The pond bottom usually has a
slope of from 2 to 5%.  (A slope of 2% would mean that for every 100cm
change in length there is a 2cm change in height.)

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The pond bottom must be clear of rocks, roots, trees, and stumps so that
later, when a net is used to harvest the fish, the net will not get caught
and tear.  If the pond bottom is already smooth and slopes well, it can
be left alone.  Or, if the pond bottom only has grass on it, the grass
does not need to be removed before the pond is filled.   In fact, once
water is added to the pond, the grass will die and rot and add nutrients
to the water.
If the pond bottom does not already slope downward, excavate (dig out)
the bottom area of the pond until a good slope for drainage is made.
Adjust the height of the strings tied to the wall markers if digging the
bottom has changed the height.
Keep the soil which was dug out of the pond:   when the pond walls are
finished, the soil can be placed on top and planted with grass.  This
fertile topsoil will root grass easily; this grass will help keep the
walls from eroding (washing away).

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The pond bottom can be excavated by hand
or by using machines, like bulldozers,
if they are available.  Remember:  if the
land for the pond is chosen well with regard
to the natural topography, only a small
part of the pond bottom will need to be
dug out.  The most important thing is
to have the pond bottom slope so that
the pond can be drained.
Build a Drainage System
A drainage system is anything that is used to empty the pond.  It consists
of the outlet system for letting water out of the pond and the drainage
ditches which carry the water from the pond away.
As stated before, the best and easiest way to have a good drainage
system is to build the pond in a place which provides a good slope -- on
a hill, for example.  This is the first step.  Then, there are many
different drainage systems which can be put into the pond.  Some of these
drainage methods are expensive; others are very inexpensive.
The drainage system must be built before the pond walls because some
drainage devices go through the walls.   (In some countries the drainage
is done by knocking a hole in the wall of the pond.   When the pond is
dry and empty, the hole is patched up.)

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One of the easiest ways to drain the pond is to place a bamboo or plastic
pipe through the base of the wall into the middle of the pond.  The end
of the pipe which is inside the pond has a screen over it to keep fish
from entering the pipe.  The other end of the pipe, the end that is
outside the pond, is plugged with wood or clay.   To drain the pond at
harvest time, the plug is pulled out.
Two other methods of draining the pond which work but are not used as
often, are the siphon and the pump.   A siphon is merely a flexible
plastic or rubber tube.  One end of the tube is in the pond near the
bottom; the other end is placed on the ground outside the pond.  A
vacuum is produced in the pipe by sucking at the end outside the pond
until water begins to flow out.   The end of the pipe inside the pond
must be kept in the water or the siphon will not work.

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The pump is usually not a good idea for a farmer because the engines
that are used to run the pumps are costly and often not available, or
gasoline to run them is costly, or they must be given frequent attention
so they will not break down.
All ponds must be drained for harvesting fish.   Also, it is a good idea
to let a pond dry out completely once every year or so to get rid of any
unwanted fish and/or disease-causing organisms.
The following are some tested, effective drainage systems a farmer can
consider for his pond.
RIVALDI VALVE  This valve was named after a farmer in Paraguay who
first used the system.  It is an easy and good method to use in a small
fish pond.  A farmer who is building only one small pond for family use
would find this valve a good choice for his needs.
The Rivaldi valve is a flexible plastic pipe.   Place the pipe on the
ground before the wall is built.   Build the wall.  Then turn up and tie
the pipe to a stake.  Tie the pipe end at a level which is somewhat above
the usual level of the water in the pond.   Keep the pipe up and tied to
the stake until it is time to drain the pond.   Then, untie the pipe and
let it lie on the floor of the pond until the water is out of the pond.
At other times, the pipe works as an overflow to let out water after a
heavy rain:  when the water level in the pond reaches the top of the pipe,
water will flow down the pipe and out of the pond.
The Rivaldi valve should have a screen over the end inside the pond to
keep fish from going out of the pond while the pond is being emptied or

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ELBOW JOINT  A variation of the Rivaldi valve, this consists of two
metal or plastic pipes connected by an elbow joint.   The joint lets the
upper pipe be turned down to drain the pond.   The joint is screwed onto
the ends of the two pipes, one of which extends under the wall and the
other above the surface of the water.   This drainage method is also
called a "turn-down" pipe because it is actually turned on its side to
drain the pond.

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BOTTOM-WATER OVERFLOW  This drain takes water directly from the
bottom of the pond where oxygen levels are the lowest.   The Rivaldi valve
and elbow joint do this also, but each of these requires that the pipe
be lowered so the pond can be drained.   The bottom-water overflow regulates
the depth of water without any need for moving the pipes.  When.
new water is added to the pond, the less-oxygenated water at the bottom
drains out automatically.
This type of drain is relatively complicated and usually difficult to
build.  For a small fish farm operation, it would probably not be worth
the effort.

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DOUBLE SLEEVE OVERFLOW  This drainage system is built like
the turn-down pipe, except a large pipe is placed over the section of
pipe which extends above the pond's surface.   This outer pipe should be
longer and wider than the inner pipe, which is placed so that it is about
equal in height to the depth of water desired in the pond.
When fresh water is required in the pond quickly because the water is
too warm for the fish or because the oxygen levels are low, all the
farmer has to do is to add water to the pond.   The double-sleeve overflow
automatically drains the stale water from the bottom of the pond.

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SLUICE  A sluice can function in a number of ways in a pond.  It can be
a screened gate in a water channel going into the pond, or a drainage
gate leading water out of the pond.
In a pond, a drainage sluice gate is anchored into the main wall by
extending the sides of the sluice into the wall so the sluice structure
stands upright.  The sluice is constructed at the center of the main wall
before the dike is built.

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The sluice can be made of wood, cement, or brick.   It can have one or two
wooden gates which are removed to empty or fill the pond.  A sluice also
can have a screen gate to keep unwanted fish from entering at an inlet
and pond fish from leaving at the outlet.

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IMPORTANT:  The wooden gates of the sluice must fit into the slots well,
but easily.  The wood will swell to make a tighter seal as it is soaked
by the water in the pond.  The slots (grooves) can be filled with several
strong, long, narrow boards which have been bevelled or notched so that
they fit together tightly.  Or the slots can be filled with single pieces
of wood.  When single pieces of wood (or a number of boards which have
been fastened tightly together) are used in a sluice, the pond is drained
and the water flow regulated by lifting the entire wooden structure out
of the groove to a height which allows some or a lot of water to flow out
of the pond.  When separate boards are used in the grooves, the boards
are taken out one at a time.   If a small flow out of the pond is desired,
only one board may be taken out.   To drain the pond, all the boards are
removed.  In a sluice having two wooden gates, the space between the gates
can be packed tightly with earth.   This will help seal the water into
the pond.

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MONK  The monk is very much like the sluice, but it is not built into
the pond wall the way the sluice is.   Sometimes the back of the monk
does touch the wall, but it is not built into the wall.   Also, a monk is
never used at the inlet as a sluice can be.

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A monk-type drainage system controls the level of water and prevents fish
from escaping when the pond is being filled.   It also allows for good
drainage of the pond.  The completed structure consists of a horizontal
drainage pipe and the vertical structure, or monk.   The drainage pipe
must be placed before the walls are built; the monk may be built outside
the pond, and placed inside later.
The drainage pipe runs from the back of the monk under the pond wall.
It should be between 20 and 40cm in diameter; if piping of this diameter
is not available, two pipes may be used.   For good drainage, place the
pipes 30 to 40cm lower than the pond bottom.   Make sure the drainage pipe
is on solid ground so that the pipes do not bend.   Bent pipes are difficult
to clean out when clogged.
The monk itself is a structure which is closed on three sides and open
in the front.  The open side should face the inside of the pond and should
be at least 30cm wide; the entire monk should be at least 40cm above the
surface of the water.
The two parallel sides of the monk, and the bottom, have grooves cut in
them:  a monk may have two or three grooves.  One groove, or part of a
groove is always for the screen.   The other groove(s) is for the boards.
Monks can be made of wood, concrete or brick.   A wooden monk should use
strong wood -- 4 to 5cm thick.
A  concrete monk should be reinforced with metal.  Before the concrete is
poured, a wooden form shaped like the monk is made and oiled.  A frame,
slightly smaller than the wooden form, is made of chicken wire, or some
other strong wire, and set down inside of the wooden form.  The concrete
is then poured into the form.   A good concrete mixture for monks is
1 part cement, 2 parts clean sand, and 4 parts crushed stone, by volume.

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If the monk is made of
concrete, the grooves can
be shaped by bending iron
rods into a "U" shape.
Remember, the grooves must
be sunk into the sides and
bottom of the monk.

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The grooves are filled by
using a series of boards -- wide
enough to fit the
grooves well and between
20 and 30cm high.  Each
board has a hook on it so
it can be lifted from the
groove easily; the boards
may also be bevelled or
notched so that they fit
together well.
If the monk has three grooves, the first groove can be a large screen.
The screen is what keeps the fish from escaping as the pond drains.
However, if the monk has only two grooves, a smaller screen can be placed
above or below the boards in the first groove.   Placing the screen at
the bottom allows water to drain out from the bottom of the pond.
HERRGUTH MONK  This is a monk with three grooves.  A large screen
is in the first groove.  The large screen is better than a smaller one
because it does not get clogged up as easily as a small screen.
The second groove holds a series of boards.   The lowest board can be a
small screen.  Water flows through the large screen in the first groove,
and through the small screen in the bottom of the first series of boards,
up and over the third series of boards into the drainage system.

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There are other ways this kind of monk can be built.   For example, the
second groove could be filled by a large wooden gate (one piece of wood
or several fastened together) which could be raised and held up to allow
a flow of water from the bottom of the pond.   It is this flow of water
from the bottom of the pond which is important.
The Herrguth monk would probably not be used in a pond which is filled
by rainwater.  In these ponds -- sky ponds -- a regular monk is used,
and the space between the two wooden gates is packed with mud to make
a watertight seal which lasts for the fish-growing season and is removed
when the pond is drained for harvest.
SOME NOTES ABOUT MONKS  Be careful with screens.  Bamboo slats
can be used instead of screening if the fish are large.   But for fry,
the holes should be less than 2mm in diameter.   Often the screens are
made by poking small holes in sheet metal.   The screen mesh can get
larger as the fish grow.
A valve is sometimes placed on the drainage pipe behind the upright part
of the monk.  This is used to control the draining speed and is easier
to do than to move the boards in the grooves.
A large catching ditch can be made in front of the monk to help with
taking fish out of the pond when the pond is being drained for harvest.
DRAINAGE DITCHES  Drainage ditches are channels which should be dug
on the bottom of the pond to help the water flow out.   Lining the ditches
with stones helps the water flow.   A small family pond does not require
this system of drains.  The only real requirement for drainage is a
gentle slope.
This is the time to build other ditches which may be needed.  For example,
if the farmer wants to use the water from his fish pond to irrigate
his land, he will want to construct the ditches or channels which will
carry the water from the pond to the field or to storage tanks for use
later.  Therefore, the farmer must consider carefully where the water
which is draining from a pond is going to go.   If the pond is being fully
drained, and the pond is built on flat ground, he should build drainage
ditches around the outside of his pond to drain the water away from the
walls.  These ditches should be 30-40cm deep.

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Water Inlet
All ponds, except for those filled directly by a spring or by rainwater,
need water inlets.  The water inlet must be constructed so that it supplies
adequate quantities and quality of water, and so that it does not allow
unwanted fish or other materials to enter the pond.   This usually means
there must be a channel of some kind to bring the water to the pond from
the source and a filter of some kind to keep the water which goes into
the pond clean and free from predators.

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A water inlet can be as simple as a bamboo pipe of good diameter running
from a water source through the wall into the pond.   Remember:  the inlet
pipe should be placed above the water level so that incoming water drops
into the pond.  In some areas, such things as bamboo strips are tied to
the end of the inlet pipe which is placed over the pond.  The water flow
into the pond is broken up by the strips and the water picks up and takes
more oxygen from the air into the pond water.
If the pond is large or is a stream-fed barrage pond, a sluice makes a
very good water inlet.  The sluice can be one piece which controls flow
when it is lifted to various heights, or the sluice can be a series of
boards slipped in and out of the grooves.
It is better to filter most pond water as it goes into the pond.  Filters
are not needed if the water is clean and clear and the farmer knows the
source is free from unwanted fish.   But if the water is muddy, or has
lots of leaves or debris in it, a filter helps keep the water quality
A filter can be placed at the beginning, middle or end of the channel
which brings water to the pond.   Usually filters work best near the water
inlet.  Filters can be made very simply.  Remember they must keep unwanted
fish out and pond fish in.
A wire screen makes a good filter.   The picture above shows a sluice with
a gate with fine screening to strain incoming water of pieces of debris
and other unwanted fish and materials.   Note the screen fits into the
water channel exactly.

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The horizontal screen at the    
left is very effective.         
Here the screen is placed       
so that the water passes        
through as it falls into the
pond.  This screen merely      
juts out from the wall at       
the inlet.                      
In the version below the        
horizontal screen has a         
vertical screen wall attached   
to it.  This short wall        
prevents fish from going        
over the screen.                

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In any variations of these kinds of filters, the screens should be
assembled into one piece for easy removal as a   unit for cleaning.
There are other ways of filtering the water:
A nylon mesh bag makes a good filter, as long as it is partially submerged
in the pond so that it does not tear as the bag catches fish or
other material from the water source.   Check it periodically.

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A sand and gravel filter is particularly useful for cleaning out fish
and eggs.  It requires building a smaller pond or tank at the water
inlet.  If a filter is built in the earth it must be lined with a waterproof

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A saran fiber filter is basically like a wire screen that is placed
horizontally underneath the water inlet.   However, it is placed in a
box standing in the water and uses saran fiber material instead of wire.
(See drawings next page.)

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These filters all have good and bad points.   All must be cleaned often
to remove debris that collects in them from the water source.  The best
filters are the sand and gravel filter, and the saran filter, but these
are more costly than the others.
The farmer should examine his water source carefully before deciding on
the kind of filter.  If the water is very muddy, or has lots of leaves
and grass in it (organic matter), he can use the wire screen.  If the
water source is free of organic material, the mesh bag will work because
it is not likely to be torn.   If the water contains unwanted fish and
eggs, as well as a lot of organic matter, the saran filter or the sand
and gravel filter is best.
To clean the filters, remove them and clean them with a brush and fresh
water.  Or flush the filter with water in the opposite direction of the
normal water flow.  This is called backwashing.
IMPORTANT:  Filters must be kept clean to be of any use.  These filters
should be cleaned each time water is let into the pond.
SILTATION TANK  One other structure which should be built at the
water inlet, when necessary, is called a siltation tank.  Silt is the
mud that is suspended (floating) in water.   Silt can become a problem
when it clogs the gills of the pond fish so they cannot breathe.  If
the water source has a lot of mud in it, a siltation tank should be
built at the inlet to the pond, or at the inlet to the first pond, if
it is one of a series.
The siltation tank can simply be a smaller pond.   The water flows into
this pond and is kept there until the mud falls out of the water and
settles on the bottom.  Then the clear water is let into the fish pond.
Siltation could also be done in a storage tank made out of old oil drums,
etc.  The important thing is that something be constructed or set up so
that the silt has a chance to fall out of the water before that water
goes into the pond.
The silt must be removed from the siltation tank or pond every so often.
The silt which is removed should be used in gardens and fields:  it is
very fertile.

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Build the Walls
The walls (dikes, dams, levees) have to withstand the pressure of all the
water in the pond.  They also have to be watertight to keep the water
inside the pond.
The construction of the walls depends upon the kind of soil in which the
pond is being built.
A soil which is a mixture of sand and clay is best.   If pure clay is to
be used, it must be mixed with other soil before it can be used.  Pure
clay will crack and leak.  Do not use turf, humus, or peaty earth.  All
stones, pieces of wood, and other materials which might rot or otherwise
weaken the wall must be removed before building begins.   If the soil
contains enough clay, the walls can be built by placing layers of soil
20cm deep over the drainage pipes and tamping each layer down until it
is compact.

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The finished height of the wall should be about 30cm above water for
small ponds and 50cm above water for large ponds.   The width of the wall
at the top should be about equal to its height.   For a large pond, the
wall is never less than 1m wide at the top; most walls are built so that
two people can walk side by side along the top.
Tamp the soil down with a simple tamping tool.   Some people use a large
rock or even their own weight by jumping up and down on the soil.  The
important thing is that the soil must be packed down very tightly.

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One way to build pond walls in soil that does not have a lot of clay or
is very sandy is to build a "key."   The key is made of clay soil (it can
be pure clay) and adds strength to the walls.   To make a key, dig a
trench (or shallow hole) about 1m deep and 1m wide in the center of the
places where the walls will be.   Then bring clay soil and pack it tightly
into the trench.  Also put a thick layer of clay soil on the pond bottom
and pack that down tightly.  The clay layer on the bottom and the key
run together as shown.  This connection of the bottom and the key helps
prevent leaking.  The drainage pipe should be placed in the clay lining.

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If the farmer has a soil which is a mixture of clay and sand, and he is
not sure it is strong enough, he may still wish to build a clay key.  Or
he can build a key using the same soil used in the wall.   This key must
be packed down very tightly.

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The type of soil determines the ways in which the pond can be prepared
so water does not leak out (see "Seal the Pond Bottom", next page).

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The soil also determines the slope of the walls.   Soil with a lot of
clay in it can have a greater slope on the outside wall than on the inside
wall.  A typical wall is built with an outside slope of 1:1 and an
inside slope of 1:2.  A slope of 1:2 means that for every change in
length of 2m there is a change of 1m in height.
Once the walls are constructed, the farmer should plant grass on them.
The grass roots help to hold the wall together and prevent erosion of
the soil.  However, NEVER plant trees on the wall.  As the tree roots
grow they will crack and destroy the wall.
Seal the Pond Bottom
The last step in pond construction is sealing the pond bottom so that
it does not leak.  If the soil has a lot of clay in it, no special sealing
is needed.  If the bottom is sand or gravel, it should be sealed to help
it hold water.  One way to seal the pond is to build a clay core into
the wall and extend the clay over the bottom of the pond as a lining.
This kind of sealing must be done when the walls are built.  After the
walls are built, there are other methods you can use for sealing the

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A pond can be sealed using hollow cement blocks, but this is expensive.
Another method of sealing the bottom calls for using a sheet liner made
of polyethylene plastic, or a rubber liner.   The waterproof sheet is
placed on the pond bottom and around the sides in one piece (the farmer
may have to tightly seal several sections together), then covered with
Another technique, recently developed in the USSR, is called a "gley" or
"biological plastic."   "Gley" can be made in the pond in this way:
   *   Clear the pond bottom of debris, rocks, and all other materials.
   *   Cover the pond bottom and sides completely with animal manure.
      Apply the manure in an even layer.
   *   Cover the animal manure layer with banana leaves, cut grasses, or
      any vegetable matter.  Make sure that all of the manure is covered.
   *   Put a layer of soil on top of the vegetable layer. 
   *   Tamp the layers down very well.
   *   Wait 2 to 3 weeks before filling the pond.         
5           Preparing the Pond
The last pages of the construction section presented several ways of
sealing the bottom of the pond so it will hold water better.  This
section tells what has to be done to prepare the completed pond for
the fish.
Conditioning the Pond
If the pond is an old one from which the fish have been harvested, plow
it completely.  Plowing turns the ground over so that it dries well.
Clear the bottom of any twigs, stumps, branches, or dead fish.  Any predators
(snakes, frogs, etc.) must be taken out by hand or poisoned (see
"Problems of Fish in Pond" for more information on this subject).  Then
smooth the bottom out again.   When the pond is dried enough, the soil
will have large cracks in it.
After the pond is plowed, cleared, and smoothed, it should be conditioned
with lime.

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Whether the pond is old or new, a
layer of lime should be placed on
the bottom of the pond.  Place the
lime on the pond two weeks before
the water is put into the pond.
Lime conditions the soil of the pond.
It is not a fertilizer, but it helps fertilizers work.   It is especially
important to use lime if the soil has acids in it which might harm the
fish.  Lime can control these acids so they are not a danger.  A farmer
who is not sure whether the soil of his new fish pond has acids in it --
because he had no place to get his soil tested, or because he has never
farmed the land -- is always safer if he puts lime on the bottom of the
Lime comes in several forms:   ground limestone; agricultural lime;
hydrated (builders') lime; or quicklime.   Of all these types, hydrated
lime is cheapest to use because it is more concentrated.
Quicklime must be used carefully:   it can burn if it touches the skin
and is harmful if breathed into the body.   Farmers should be warned to
use quicklime only with extreme care.
Lime should be put on the pond bottom at the following rates for a new
          Ground Limestone          1140kg per hectare
          Agricultural Lime         2270kg per hectare
          Hydrated Lime              114kg per hectare
          Quicklime                  200kg per hectare
A word about limestone:  In many areas of the world, limestone can be
found locally.  It is a soft stone and may be ground by the farmers
themselves.  It is a good idea to let farmers know whether or not limestone
is available locally and to help them identify it if they can not
already do so.
Filling the Pond
After the lime has been on the pond bottom for at least two weeks, let
the water in slowly.  The water should fall from the water inlet into
the pond below, so that the water mixes with oxygen from the air as it
falls into the pond.

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The water should not go in too quickly.   If the water goes in too fast,
the pond bottom will get stirred up and make the water muddy.
Let the pond sit for a few days after it has been filled.  Then check the
quality of the water in the pond -- before adding the fish.
Fish growth depends greatly on the quality of the water used in the pond.
And the quality of the water depends upon where it comes from and what
kind of soil it travels over.   Testing the water quality means making
sure that all the factors which relate to water are right for the fish.
These factors are:  temperature, oxygen content, pH, turbidity, hardness,
alkalinity, and nutrient availability (source of food for the fish).  The
farmer does not need to know these particular words to raise fish well,
but he does require a working knowledge of the factors that are part of
the water world in which the fish live.
Fish are cold-blooded animals; that is, their body temperatures depend
upon the temperature of the water in which they live.   Every fish species
has a temperature range within which it grows quickly.   This is called
the optimum temperature range, and it means that this fish grows best
at temperatures within that range.   In a fish pond, the fish should live
at their optimum to grow well.   However, since fish have different
temperature requirements, the farmer must choose the fish which will
grow best in the temperature range of his pond.
Here are some of the common pond fish and their temperature ranges:
   Genus, species          Common name             Temperature [degree C]
Tilapia mossambica          tilapia                   25-35
Osphronemus goramy          gourami                   24-28
Puntius javanicus           tawes                     25-33
Cyprinus Carpio             common carp               20-25
Ctenopharyngodon idellus    grass carp                25-30
Anguilla japonica           eel                       20-28
This chart shows that all the fish on this list could live in water that
is 25 [degrees] C (77 [degrees] F).   The chart also shows that an eel can live and grow well
at 20 [degrees] C, but that the tilapia and the grass carp will not do well at 20 [degrees C]
because this temperature is below the range in which they are comfortable.
When the temperature goes higher or lower than this optimum, fish will
not grow.  Eventually, if the temperature goes too high or too low,
the fish will die.
The farmer must watch the temperature in the pond water carefully,
especially if the weather becomes unusually hot or cold.  If it is
possible, it is a good idea for a farmer to use a thermometer to find
the temperature of his pond water.   This can be done by using a
thermometer which is used for taking temperatures when people are sick.
The most important step is to guide the farmer to stock fish which will
do well in the normal temperature ranges of his area.   Then the temperature
of the water will not generally be a problem, except in cases of
unusual weather.

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Some experienced fish growers can judge the water temperature by putting
their arms in the water.  Most people cannot tell temperature this way.
But if the right kind of fish has been chosen for the pond, the farmer
need only watch the fish to be able to judge the temperature of the pond
water.  If the water is becoming too hot, the fish will not eat and will
move very slowly.
If the farmer sees this behavior in his fish pond, he can take out some
of the pond water and put in new, cooler water.   Another way of protecting
the water from getting too hot is to find a way to shade the pond,
so that the sun does not shine directly on the water.   The shading should
be temporary because sunlight is important to the success of the pond.

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The picture on the previous page shows a fish pond being shaded by
palm tree branches stuck into the ground around the edges of the pond.
As soon as the temperature of the water goes down, the branches are
Temperature, however, usually does not act alone.   If the fish are
showing signs of distress because of hot weather, it is often a problem
caused by high temperatures and low oxygen content.
The farmer cannot see oxygen, so it may be hard for him to realize
its importance.  But it is worth taking the time to help a pond owner
understand oxygen as a critical factor in the success of his fish pond.
Oxygen lack is a problem which can occur at any time during fish pond
operation, and there is a good chance the farmer will have to depend
only upon his own knowledge of the problem and its cause to solve it
Fish, like all animals and human beings, need oxygen to breathe and,
therefore, to live.  Through a process called respiration, fish and
human beings take in oxygen and give off carbon dioxide.  Fish will not
grow well when the oxygen supply is low; and if the oxygen level gets
too low, they will die.
Oxygen is a gas.  Human beings get the oxygen they need from the air.
They cannot see it, or smell it, but without it they would die.  Most
fish can only get oxygen from the water in the fish pond.  The farmer
cannot see the oxygen in the water either, but he should realize that
it must be there in sufficient quantity for the fish to live.
Oxygen troubles arise in a pond when the supply of oxygen is used up
faster than oxygen is put into the pond.   This happens to human beings
too -- if too many people are shut into a room with no windows or airholes,
the respiration of all these people uses up the oxygen.   Soon,
there is too much carbon dioxide in the air.   The people have trouble
breathing until a window is opened and fresh air containing oxygen is
let in.
This is exactly what happens to fish in the fish pond.   The fish are shut
up in the pond, and if there is not enough oxygen entering the pond,
they will have trouble breathing.   And, if the problem continues, they
will die.
Water contains tiny plants and animals called plankton.   Most plankton
are so very small that they cannot be seen without using a microscope.
The plants are phytoplankton:        The animals are zooplankton:
<FIGURE>                             <FIGURE>

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Water also contains higher orders of vegetation.   These plants are much
larger than the phytoplankton.

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The fish and the zooplankton use oxygen and give off carbon dioxide in
respiration; the phytoplankton and higher plants use carbon dioxide and
sunlight to produce oxygen during a process called photosynthesis.

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The oxygen in a fish pond also is used up by the process of decay.
Dead organic matter -- leaves, fish, other plant and animal material
present in the pond, use up oxygen in the decay process called
oxidation.  Oxidation and respiration go on both day and night, while
photosynthesis can take place only during sunlight hours.
Therefore, there are times during the day when the oxygen levels in the
pond can be very low, and oxygen may have to be added to the water.
Oxygen can be added to the pond water by taking out some of the old
water which is low in oxygen and adding new water.

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The new water should be sprayed or bubbled into the pond so that the
water picks up oxygen from the air as it falls into the pond.
Oxygen also can be added to pond water by:
Stirring up the water already in the
pond.  Some farmers beat and stir the
water with poles.

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Some pond owners use oars to stir the water.

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Other owners run small motors
to bubble the water in the pond.

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In addition, winds which are strong enough to ripple the surface of the
water in the pond help the air and water to mix.   Remember:  any disturbance
of the water made by man or by nature helps put oxygen into (aerates)
the water.
Life under the water is a new idea to many farmers.   And it is sometimes
difficult to understand that the balances which exist on land are also
present in the water.  Oxygen is produced and used both above and below
the surface of the water.  The fish pond does well only when oxygen
production and oxygen use are in balanced relationship.
If the farmer understands the balance --
how oxygen is added and how it is used
up, he will know how to watch for trouble
before it happens.  For example, if
the color of the water changes from green
to clear -- in a few hours or a day --
the phytoplankton are not producing
enough oxygen.  If the fish are at the
surface of the water and seem to
be gulping air, they may need oxygen.
Early in the morning, before
the sun comes up, or a long period
of no sunshine can be bad times because
the phytoplankton need the
sun to produce oxygen.  Long periods
of hot weather can create oxygen
problems because the pond water
gets warmer, and ways water cannot
hold as much oxygen as cool water

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The following table shows the difference in oxygen levels at various
points in the day.  For example, at 6 am, the temperature has remained
steady, but the dissolved oxygen level has dropped to 6.3mg.  At 6 pm,
after a sunny day, the dissolved oxygen level is 16.3mg.
This table also shows that on a typical day a pond's temperature
does not vary greatly.  This illustrates why oxygen as a separate
factor is much more important than is temperature.
Time of Day         Temperature [degree] C    Dissolved Oxygen, mg/1
    2 am                   29                           9.8
    6 am                   29                           6.3
   10 am                   29                           6.7
    2 pm                   30                           9.4
    6 pm                   29                          16.3
   10 pm                   29                          10.7
Oxygen is measured in either milligrams per liter (mg/l) or parts per
million (ppm).  One milligram per liter of oxygen means that there is
one milligram of oxygen dissolved in one liter of water.  One part per
million is approximately equivalent to one milligram per liter.
Fish begin to be stressed when the oxygen-level falls below 4mg/l.  For
best growth, the oxygen levels should be above 5mg/l, but not more than
15mg/l.  Above this level of oxygen, supersaturation often results
(too much oxygen).
Sometimes, if there is a lot of sun and a lot of wind activity at the same
time, and if the temperature is low, the water can become supersaturated
with oxygen.  Supersaturated water contains more oxygen than water can
normally hold at a given temperature; it is a temporary condition.  This
condition can place stress on the fish.   However, it does not happen
very often in small ponds because the wind is not usually able to aerate
pond water as  thoroughly as it can in a large pond.
To determine the exact oxygen content
of a pond, certain chemicals and
equipment are needed.  Dissolved
oxygen is usually determined in
the laboratory by the Winkler
Method.  Now, however, there are
field kits available ((Hach, LaMotte).
These kits are, however, expensive,
and certainly will not be
available to most farmers.

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These three factors are not the same thing -- each one is a measure of
a certain characteristic or characteristics of the water in a fish pond.
Each of these factors can be measured exactly if samples of pond water
can be taken to a laboratory to be analyzed, or if chemicals are
available for testing the water in the field.   Certainly if such
testing is possible, it should be done.
However, many pond owners are not able to get their water tested and
they do not have the right chemicals and equipment to do the tests
themselves.  For these people, it is best to stress the importance of
using lime in their ponds.  Lime is the proper treatment to correct
imbalances in these factors, each of which is discussed in some detail
pH.  pH is the measure of hydrogen ions ([H.sup.+]) in the water and is measured
on a scale of 1 to 14.  If the pH is between 0 and 7, the water is
considered to be acid.  If the pH is at 7, the water is neutral (not
acid or basic).  A pH of 7 to 14 means the water is basic.  Fish grow
best in a pH of between 6.5 and 9.0. Fish are very sensitive to low
pH, or, in other words, to water which is acid.   Most pond fish will die
if the pH falls below 4 for a very long period of time.
Sometimes the pH of a pond can change quickly.   For example, a heavy
rain may carry acid from the soil in the dikes into the pond water.
The best way to get the pH back to neutral is to add limestone
(calcium carbonate) to the water by spreading it on the pond bottom
or on the surface of the water.   A fish like tilapia can tolerate
pH from 3.7 to 10.5, but below a pH of 5, they are stressed and they
will not eat.
Some people measure pH by tasting the water. If the water tastes sour
or salty, it has too much acid in it.   Another way to find out pH is to
know where the water is coming from.   If the water comes from a swamp,
bog, or other place where the water is pretty stagnant and contains a
lot of decaying material, it may be acid.   Most water, however, has a
pH which is very close to neutral.   If the water comes from a river or
lake, it is not likely to have a pH that will harm the fish. If the
local fish do well in the water, the pond fish probably will do well
Litmus Paper.  Some farm owners find out their pH by using litmus paper,
or pH paper.  These are thin strips of paper which have chemicals on
them so that they change color when they are placed into the water. If
the water is acid, the paper will turn one color; if the water is basic,
the paper turns a different color.   The color on the paper is compared
to a color chart which will give the pH for that color.   There are also
electronic meters which measure pH, but these are expensive and not
necessary in a field situation.
Hardness.  Hardness is the measure of total soluble salts that are
dissolved in the water.  These salts, usually calcium ([Ca.sup.++]) and
magnesium ([Mg.sup.++]), help the fish grow healthy bones and teeth.  Also,
the foods the fish eat, like the phytoplankton, need calcium and
magnesium for growth.  Water that contains many salts is called "hard"
water; water that contains few salts is called "soft" water.
Hardness is related to the pH of the water, but unlike the pH, hardness
stays constant throughout the day.   Hardness can be measured in a laboratory
or by using a field kit with chemicals.   Hardness should be between
50 and 300ppm in the pond for best fish growth.
There are several ways a farmer can tell if he has very hard water without
using chemicals.  One method is to look closely at the pond walls where
the water line is.  If there is a white line on the wall of the pond
where the water was touching the pond before the water level fell, there
are salts present in the water which have dried on the pond walls.  This
water probably has a lot of salts.   Hardness is important to fish.
Another way a farmer can tell if the water is hard is to wash his hands
with it at the side of the pond.   If the soap takes a long time to lather,
and if the lather does not stay very long, the water is hard.  If the
water is soft and does not contain many salts, it lathers very easily and
is hard to wash off.
If the water is too soft, the farmer can increase the hardness by adding
lime to the water.
Alkalinity.  Alkalinity is a measure of the acid-combining capacity of the
water; or it is also called its buffering ability.   Alkalinity measures the
amounts of carbonates and bicarbonates in the water.   These are materials
which mix with acid in the water.   The result of the mixing is that the
acid is not as strong.  Waters which have an alkalinity of 50 to 200ppm
are the most productive for fish.   Alkalinity, like pH and hardness, can
be corrected and controlled by adding lime to the pond.   The relationship
among alkalinity, hardness, and pH can be summarized like this:
           Low Alkalinity = Low pH = Low Hardness
           LIME TO THE WATER.
Turbidity is the term for the suspended dirt and other particles in water.
Turbidity can be a problem, especially in shallow ponds, if the dirt and
particles prevent sunlight from reaching the plankton, so that the phytoplankton
cannot produce oxygen.  An operating pond can be turbid if there
are bottom feeders such as common carp stirring up the bottom mud.  Or,
turbidity can result from a water source which has a lot of silt in it.
Turbidity can be measured by just looking at the pond water.  Or turbidity
can be measured by using a device called the Secchi disc.  The Secchi
disc is also used to determine the total productivity of the pond.

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A Secchi disc is about 30cm in diameter, painted white and black or
just white, and has weights or heavy objects hanging on it to make it
sink straight down into the water.   The disc is suspended on a rope or
a long piece of wire that is marked off in centimeters from the disc up.
A Secchi disc can be made out of wood or metal -- as long as it will
sink.  The disc does not have to be very complicated. It does not have
to be round, either.  It can be any shape, as long as it has some white
paint on it to help it be seen under the water.   The disc can be made
from a tin can pounded for this purpose.

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When the Secchi disc goes into
the water, it will sink straight
down and disappear from sight at
some depth.  If the disc disappears
at 30cm in depth, the pond is
turbid.  If it disappears immediately,
either it is very turbid
(brown in color), or it is very
fertile (productive), if green in
Turbidity also can be measured without a disc, but this requires somewhat
more experience.  The farmer stands in the pond and sticks his arm under
the water.

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If his hand disappears when
the water is about elbow
deep, the water is not too
turbid.  If it disappears
before the water reaches the
elbow, the water is either
turbid or very productive.
If the entire arm from hand
to shoulder can be seen under
the water, it is not turbid
at all, nor is it very productive
(it does not contain
enough fish food).
One way to clear up muddy water is to scatter twelve bales of hay per hectare
around the edges of the pond.   The hay will help to settle the mud
and can then be removed easily from the pond edges.   However, do not use
this method in very hot weather, because the hay will begin to decay
very quickly and will begin to use up oxygen in the pond water.  If the
pond water continues to have a lot of silt in it, the farmer should
consider adding a siltation tank (see "Construction").
All fish require certain elements to grow and reproduce.  These essential
elements are:  carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium,
sulfur, calcium, iron, and magnesium.   Some other elements called trace
elements, are needed only in small amounts.   If these elements are missing,
or present in too small quantities, the fish will not grow well.
                    Fish Require a Balanced Diet
                            of Elements
                      Carbon          Potassuim
                      Hydrogen        Sulfur
                      Oxygen          Calcium
                      Nitrogen        Iron
                      Phosphorus       Magnesium
                         Plus trace elements
Fish get these elements from the pond soil, the pond water, and the
food they eat.  Some fish ponds lack elements that are necessary to
fish.  In these cases, it is necessary to add fertilizers to the water.
Fertilizers are simply materials which contain the missing elements.
The elements most often missing, or in short supply in fish ponds,
are nitrogen (N), phosphorus (P), and potassium (K).

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Fertilizers containing these
missing elements are added
to the fish pond to help the
growth of the fish and of
the plankton the fish use
for food.  Fertilization
is discussed in the following
Fertilizers are materials added to the pond to make the water more
fertile (productive).  As stated before, fertilization is sometimes
necessary to help a pond provide the nutrients directly needed for
fish and plankton growth.  As a major food source of fish, plankton
must be kept healthy and in good supply.
Fertilizer supplements the elements the pond gets from its own water
and soil.  This is especially necessary in ponds made in soil which
has used up the nutrients once available.
A pond which has a lot of phytoplankton is often a bright green color.
This color indicates a "bloom" of algae.   In a normal bloom, the Secchi
disc disappears at about 30cm depth; when the Secchi disc disappears
at 20-40cm, the pond is very productive and fertile.   No fertilizer
is needed in a pond under these conditions.   Also, if the farmer places
his arm in the pond and his am disappears from sight at the elbow,
the pond does not need fertilizer.
There is one more condition when no fertilizer is needed.  Sometimes
a pond can become too fertile.   If the Secchi disc disappears at only
15cm, the "bloom" is too thick.   The thick layer of green blocks the
sunlight from the pond and no oxygen can be made by the phytoplankton.

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In this case, there is too much
fertilizer, and the farmer must
take off some of the thick layer
of algae formed at the top of the
pond and stop using fertilizer
until the pond has recovered a
normal fertilizer level.
If the Secchi disc can still be seen at 43cm, for example, or if the
farmer can still see his entire arm from fingers to shoulder under the
water, there is not enough plankton.   And it is necessary to add fertilizer
to the water in order to prepare the pond for the fish.
One other factor which determines the need for fertilizer is the quality
of the soil.  If the soil is very productive, the need for fertilizer
is small; if the soil is not productive, the need is greater.  A farmer
should know that the fertilizer he uses on his fields, if he uses one,
can also be used in his fish pond.   The fish pond soil is often very
like the soil of the fields around it.
The kinds of fertilizers used in fish ponds vary greatly, depending on
the amount of money which can be spent and what is available.  Many
fish pond owners use organic fertilizers, or fertilizers that come
from living things; such as cow dung--because it is available on their
farms.  Some big pond owners like inorganic fertilizers, or chemicals
made by man, like the superphosphates.   But these chemical fertilizers
are expensive and sometimes hard to get.
Choosing fertilizer can be difficult.   The following paragraphs provide
more detail about organic and inorganic fertilizers and some guidelines
to the proper use of each.
Organic Fertilizers.  Organic fertilizers can be plant or animal
products, such as:
Vegetable matter.  Chopped up manioc, sweet potatoes, or banana leaves,
kang kong, guinea or napier grass, or other such things that have been
allowed to rot for a while.  The amounts of vegetable matter used as
fertilizer can be as high as 5,000 kg/ha.
Liquid manure.  Mostly animal urine containing uric acid, a source of
nitrogen.  It is washed out of buildings where animals are kept into the
ponds and used in very small amounts by mixing it with other organic
fertilizers, such as cow or pig manure.
Household scraps.  Including garbage, grass cuttings, rice husks, and
human sewage, also called "night soil".
Animal manure.  Almost any kind of animal manure can be used as
fertilizer, including cow, pig, duck, or chicken dung.   Some manures
are better fertilizers than others.   The best way to use this kind of
fertilizer is to make a "soup" of it in a tank by mixing it with water.
Use the liquid part of the "soup" in the pond.  Animal manure can also
be placed in a burlap bag hung from a stake in the water.  This way,
the nutrients from the manure will be released slowly into the water
without the manure itself clogging up the pond bottom.   If this cannot
be done, then pile the manure in the corners of the pond.  Do not use
too much manure:  decaying manure uses up the oxygen in the pond --
particularly in hot, humid climates.

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The best way to use these sources of fertilizer is to mix them all
together in what is know as a compost pile.   A compost pile is simply
a pile of these organic materials which has been left to rot.  As
the materials decay together, they produce a substance which is a
very good fertilizer.  Compost piles are important:  they provide the
very best kind of organic fertilizer for fish ponds and, in many cases,
they cost nothing.
                     Making a Compost Pile

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For many years, compost has been made this way:
   *   Pile organic matter, such as leaves, straw, grass, rice husks
      or other plant material and household scraps about 30cm high.
   *   Put a layer of animal manure (chicken, cow, Pig, duck or whatever
      is available) on top of the first layer.
   *   Sprinkle ashes and lime on the manure.
   *   Repeat these layers of plant material, manure, ashes and lime
      until the pile is about 1.5m high and 1.5 m wide.
   *   Keep the pile moist, but do not let it get wet.
   *   Turn the pile every three weeks with a shovel for about 3 months.
   *   Use the pile in 3 months.   It will have decayed and shrunk to
      about 1/10 of its original size.

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There is now a faster way to make the compost ready to use as fertilizer.
   *   Make the same 1.5m x 1.5m pile of plant material, manure, and
      lime.   This time, however, use more household garbage and animal
      manure.   (Animal manure supplies nitrogen, an element used by
      plants during the decay process.  A good compost mixture is about
      1 shovelful of manure to 30 shovelsful of the other organic
   *   Mix the material well.   Then cut all of it into small pieces, using
      a shovel, machete, scythe, etc.  The pieces should be about 3 to
      5cm long.   Cutting the material speeds the rotting process.  (If
      animal manure is hard to get, add some inorganic fertilizer containing
      nitrogen to the compost pile.)
   *   Turn the pile every few days.   Use a shovel to keep it well-mixed.
      Compost piles can get too hot in the middle if they are not turned
      and mixed.   Put a stick into the middle of the pile.  Leave the
      stick in the pile for 3 minutes, and then pull it out.  If the stick
      is hot, dry, or smelly, the pile must be turned so that the inside
      of the pile is now on the outside.
   *   Keep the pile moist, but not wet.   Protect it from the rain.   Animal
      urine can be used to keep the pile moist and helps add nitrogen to
      the pile (pig urine is best).  A compost pile made in this way will
      be ready for use in only 3 weeks.
When ready, pile the compost in the corners of the pond and restrain it
with a screen; or cover the compost with a layer of mud to hold the
plant material in place so it does not float into the pond.  The compost
releases its nutrients into the pond water gradually.
Fertilizer should be applied at a rate determined by the area of your
pond.  Area is the length of the pond multiplied by the width.  For
example, if the pond is 10m wide by 20m long, it has an area of 200
square meters ([m.sup.2]).  This is equivalent to 2/100 of a hectare.   The
measurements used for pond area are:

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               1 are = [100m.sup.2]
               1 acre = 40 ares = [4000m.sup.2]
               1 hectare = 100 ares = 2.5 acres = [10,000m.sup.2]
To fertilize a [200m.sup.2] fish pond with chicken manure, at a rate of 200
kg/ha, you must only use 4 kg as follows:
          [200m.sup.2]   =    x           :   200 (200)    =   X ;   X   =  4 kg
       ________               _________        _________
       [10,000m.sup.2]        200 kg/ha        10,000
Most ponds are not as big as one hectare, so the farmer will have to
determine his pond's area before using the manure.   It will be hard for
most farmers to calculate application rates in this way, but it is
probably easy for you to develop some standard measures a farmer can
use which are based on the average-sized pond in your area.
Often fish ponds are managed in conjunction with other animals.  Stables
are built right over the edge of the ponds, and the manure and urine
from a certain number of animals are allowed to fall directly into the
pond.  This efficient system works well for fish which can use animal
manure directly as food.  Pigs are often used like this because pig dung
makes a good food for some fish.   Fish ponds which share the area with
a number of ducks also show high yields of both ducks and fish.

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For the first fertilizer added to a new pond, some common rates of
application of animal manures are:
                 Cow dung       1000 kg/ha
                 Pig dung        568 - 1704 kg/ha
                 Chicken dung    114 - 228 kg/ha
REMEMBER:  Except for compost fertilizer, only one kind of fertilizer
is needed at one time in a pond.   Only use one of the application rates
each time the pond is fertilized, or a combination of fertilizers with
different rates to make up one rate.   That is, you can use 1000 kg/ha
of cow dung, or 500 kg/ha cow and 171 kg/ha chicken dung, or about 300
kg/ha cow, 57 kg/ha chicken, and 284 kg/ha of pig dung.   After you fertilize
keep an eye on the pond.  Try not to over fertilize -- too much is
just as bad as not enough.
After the first application of fertilizer, application rates do not
have to be as high.  Many older ponds do not need as much fertilizer
because the natural life of a pond tends towards becoming more fertile
the older it gets.  However, each time the fish are harvested they
take part of the pond's productivity with them.   That is why older
ponds are still fertilized -- even though they may need less fertilizer
than new ponds.
Inorganic Fertilizers.  Inorganic fertilizers are chemical fertilizers
that dissolve in the pond water and provide their nutrients immediately.
Originally, inorganic fertilizers supplied nitrogen, phosphorus,
and potassium, and they were called the NPK fertilizers.  Some typical
NPK fertilizers were8-8-2 (NPK) and 20-20-5 (NPK).   This simply
referred to the mix of fertilizer that each bag supplied; for example,
8 measures of nitrogen, 8 measures of phosphorus and 2 measures of
potassium.  Recent studies show that if enough phosphorus is available,
the plants in the pond produce their own nitrogen, and that potassium
is present already in small amounts in fish.   Presently, the only
element needed by fish that may be lacking in the fish pond is the
element phosphorus.
Now, the most common inorganic fertilizers used in fish ponds are the
phosphorus fertilizers -- basic slag, powdered single superphosphate,
granular double superphosphate and triple superphosphate.  Some of
these fertilizers can last as long as three years in the pond, so even
though they are expensive initially, they are often used in fish ponds.
Research shows that the best fish growth occurs when phosphate fertilizers
and organic fertilizers are used together.
Application rates of phosphate fertilizers are:
                Basic slag                   25-30 kg/ha
                Single superphosphate          114 kg/ha
                Granular double superphosphate  57 kg/ha

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Fertilizers have one purpose--to provide better growth of fish in ponds.
Many organic and inorganic fertilizers are good.   Watch the pond carefully
for signs concerning a need for fertilizer.   As long as the water
is a green color, the pond is in good condition.   Remember:  it is
always best to do two things at once--wherever possible use fertilizers
which can be used as food by the fish.
Now that the pond has been filled, the quality of the water tested, and
the fertilizer added, the last step in preparing for the fish is to
make sure that the food supply in the pond is sufficient for the fish
that will be put into the pond.
It is important to be sure that fish have good food.   Feeding and
fertilization work together to make the pond successful.
The growth of fish in ponds is directly related to the amount of food
available in the pond.  The pond must provide all the food and nutrients
fish need.  But all fish do not need the same kinds of food:  different
species eat different types of food, and fish eat different foods depending
on the stage of their life cycle.
Newly-hatched fry eat from their yolk sacs until the sacs are gone.
The fry then eat the smallest phytoplankton in the pond.  As the fry
get bigger, they can eat bigger foods.   Adult fish eat the things that
their particular kind of fish enjoy--plankton, higher plants, worms,
insect larvae, etc.
Fish foods can be natural (those found naturally in the pond) or supplementary
(those foods added to the pond).
Natural Foods.  These foods are the phytoplankton, zooplankton, detritus,
snails, worms, insects and insect larvae, small plants like duckweeds
and various other weeds and grasses that can be found in a fish pond.
(See illustrations of Natural Foods at the end of this section.)   Also,
if the fish is carnivorous and eats the flesh of other animals, small
fish are a food source.
Some fish eat all these foods; some prefer only one kind of food.
Often a fish will choose one kind of food over another, even though
either of the foods would be eaten by the fish if the other food were
not available.  Natural foods are the best foods for fish.   The farmer
should encourage, as much as possible, the growth of these natural
foods--through maintaining the quality of his water, proper fertilization
of the pond bottom and the water, etc.
Sometimes, however, the farmer must add food to the pond because the
pond is not producing enough food for good growth.   The best supplementary
foods a farmer can put into the pond are extra natural foods.
But there are a great number of other foods which fish will eat.
Supplementary Foods.  Almost anything can be used as a supplementary
food, depending on the fish species in the pond.   Typical supplementary
foods are:  bread crumbs, rice bran, fish meal, ground-up maize,
broken rice, soy bean cakes, peanut cakes, corn meal, cottonseed oil
cakes, oats, barley, rye, potatoes, coconut cakes, sweet potatoes,
guinea grass, napier grass, kang kong, manioc, water hyacinth, wheat,
silkworm pupae, and left-over animal feeds and some animal manures.
As stated previously, the kind of extra food depends on the kind of
fish.  Tilapia, for example, will eat almost anything, including the
supplementary foods listed above.   This is one reason why they, are
such very good pond fish.  The silver carp, on the other hand, will
eat only phytoplankton, even when it is a fish of marketable size.
The farmer must know what his fish will accept before he puts the
fish into the pond.
Some of these supplemental foods are better at encouraging growth than
others.  The value of each food is measured in terms of how quickly
and well it can help the fish gain weight.   The amount of a food that
can be converted into fish flesh by the fish is called the conversion
ratio.  And because these foods are given to help the fish grow, each
food has what is known in various places as a growth co-efficient,
food quotient, or its nutritive ratio.
The food quotient is figured by dividing the total weight of the food
by the total increase in weight gained by the fish over a period of
time.  This is done as follows:
            Food Quotient = weight of food given
                            increase in weight of fish
For example, a fish weighing 100g is fed a supplementary food at a
rate of 5% of his body weight, or 5g per day.   The fish weighs 160g
at the end of a 30-day period.   Therefore, the food quotient of this
particular food is:
            Food Quotient = 5g (30 days)  =   150
                            ____________     ___
                            (160-100g)        60
            Food Quotient = 2.5
In other words, the fish has been able to use about 2.5g of food to
gain 1.0g of weight a day.  This is a good conversion ratio.
The table shown here lists food quotients of some kinds of supplementary
foods used with common carp.   The lower the value of the quotient,
the better the food was used by the fish.   For example, dried silkworm
pupae help the fish grow faster than do fresh silkworm pupae.  REMEMBER:
the conversion of foods depends upon the ability of the individual
fish to use the food given to it.   And that ability differs according
to species.
     FOOD                                       FOOD QUOTIENT
     Fresh silkworm pupae                        5.0 - 5.5
     Dried silkworm pupae                        1.3 - 2.1
     Chironomids                                  2.3 - 4.4
     Fish meal                                    1.5 - 3.0
     Rice bran                                          5.1
     Soy bean cake                                     2.2
     Clam meat                                          1.3
     Cottonseed cake                                    3.0
     Dehydrated blood                            1.5 - 1.7
     Maize                                        4.0 - 6.0
     Source:   Bardach, et. al., Aquaculture
It will be hard or impossible for many farmers in your area to figure
these ratios and quotients.  For the farmer who is new to the effort
and has few resources, it may be a good idea to direct him to the
supplementary foods having the best conversion ratios for his fish.

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6           Managing the Pond
It should be clear by now that much of the success of a fish pond depends
upon careful planning.  Before the farmer could build the pond, it was
necessary for him to think through why he wanted the pond -- for food,
profit, or both, what kind of ponds he could build on his land and what
kind or kinds of fish are best suited to his climate and pond conditions.
Only when all these factors were thought out could the pond be built.
Now, with the pond constructed, fertilized, and otherwise prepared for
the fish, the farmer is ready to put the fish into (stock) the ponds
and get to the business of raising fish.
Stocking is the word used to describe the act of placing the fish (stock)
into the pond.  The stocking density is used here to refer to the total
number of fish which can be put into (stocked) in a pond.

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The stocking rate is the term used to refer to the number of one species
which are put into a pond.  Therefore, in a monoculture pond, the
stocking rate is the same as the stocking density because there is only
one kind of fish.
In a polyculture of Chinese carp, however, the stocking density, or the
total number of fingerlings, may be 20,000 per hectare.   Of this total,
the stocking rate looks like this:   grass carp are stocked at a rate
of 5,000; 5,000 are bighead carp; 10,000 are silver carp.

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Stocking rate and density are important.   There is only enough food and
room in a pond for a certain number of fish.   The good growth of fish
depends upon putting the right number of fish into the pond.
The age of the fish must also be considered when stocking ponds.  For
example, more fingerlings can be placed in a pond than brood fish, because
fingerlings require less food per fish than brood fish.   If the food
available in the pond is not supplemented, proper stocking rates and densities
are even more important.
The farmer must know how many fish he can put into his pond so that he
can get the right number--either from the market or from a local stream
or lake.  He should remember, when he decides upon this number, that
some of the fish will die--both when they are put into the pond and
later.  The following paragraphs provide some guidelines to use when
stocking a pond with some of the more common pond fish.
Common Carp.  Stocking densities differ with the age and size of the
fish.  In general, the more volume of water a carp has, the better is
its growth.  This assumes that the pond contains enough food, and the
water temperature is right.  The best growth of common carp has been
shown with stocking densities of about 10,000 to 20,000 fish per
hectare; more with fry; less with post-fingerlings.   Some ponds use
running water, and in these ponds, they have been able to stock up to
850,000 fry per hectare with only a 20% mortality rate.
Tilapia.  Tilapia have been stocked in amounts ranging from 1000 fish
per hectare to about 50,000 fish per hectare when supplementary food
was provided.  But stocking densities really depend on the rates of
reproduction of tilapia, and whether they can be separated by sex or not.
Chinese Carp.  In general, the stocking rates can only be found by trial
and error, and often will be different from time to time, depending upon
the availability of fry.  In Malaysia, a ratio of carp stocking has been
suggested of 2:1:1:3 for grass carp, bighead, silver carp and common carp.
This means that if there were a stocking density of 7 Chinese carp, 2
fish would be grass carp, 3 would be common carp, and there would be only
one each of bighead and silver carp.   This is a good stocking rate for
this density.  The density for a given pond has to be figured in terms
of what the pond can support.
Indian Carp.  Stocking densities of Indian carp are not widely known.
Some densities range from 4,000 to 11,000 fry or fingerlings per hectare,
but again, the density depends upon the amount of food available to
the fish.
When stocking ponds to produce market-size fish, remember that the more
fish stocked, the more food must be available for the best possible
growth in ponds.
The following paragraphs describe the proper methods for carrying new
stock from the market or river to the pond, and for placing them into
the pond.
There are some general rules which apply when bringing fish from one
place to another:
   *   do not handle the fish too much
   *   make sure the fish get enough oxygen
   *   keep the fish from getting too warm or too cold
   *   stock or transfer fish in the early morning when temperatures
      are lower and the fish are less active.
If fish are stocked so that there is enough oxygen, no temperature
difference between the stocking water and the pond water, and they are
not touched, the fish will not be stressed and will survive the stocking.
Here are more details concerning the stocking of fish at different
stages in the life cycle.
When fry are being moved for a short distance only, for example, from
a nursery pond to a rearing pond, they usually are carried in small plastic
or metal tubs, or in baskets.

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To move fry successfully:
    *   Scoop the fry out of the river or pond in jars, cups, or
       small nets.

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    *   Put the fry into a bucket of water.
    *   Carry the bucket to the pond where
       the fry will be placed.
    *   Check the temperature of the water
       in the bucket; it should be the
       same temperature as the water in
       the pond where the fry will be

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    *   Add water from the pond to the bucket slowly -- until the
       temperature of the water in the bucket is the same as the
       temperature of the water in the pond.
    *   Tip the bucket slowly into the pond, and let the fry swim
       out into the pond themselves.
           TO BE EXPECTED.
Moving Fry for Longer Distances.   If the fry are to be taken from a
market or river which requires a few hours travel or a long distance,
they must be protected better.   One method, which can also be used
for fingerlings (and some small adult fish), is to:
    *   Place fry into plastic bags filled 1/3 with water.
    *   Fill the rest of the bag with oxygen.   The oxygen is
       put into the bag with a hose placed directly into the
       water so that the oxygen bubbles into the water.

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    *   Tie the bag tightly so that the
       oxygen does not leak out.

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    *  Place the plastic bags into tin boxes or cardboard boxes
       or in woven grass bags.  These containers give added

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    *   Change the water in the bags after 6 hours.  The oxygen will
       last only that long.
    *   Make sure the bags do not get too hot and that the temperature
       of the water in the bags stays at about the same
       temperature as the water from which the fingerlings or
       fry were taken.
    *   Place the bags in the pond unopened until the water temperature
       inside the bags is about the same as the temperature in the pond.

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    *   Open the bags and let some pond water in.
    *   Let the bag fill up slowly, and the fish will swim out into the
       pond by themselves.
This process may take a little while, but it is far better to take the
time than it is to lose the fry.   NEVER POUR FRY INTO A POND.  This will
shock them and kill them all.
Stocking Fingerlings.  Fingerlings are stocked in the same way as fry.
Always remember that the water in their container must be at the same
temperature as the water in the pond.   Then let the fingerlings swim out
of the container into the pond by themselves.   DO NOT POUR FINGERLINGS
INTO THE POND.  They may die because of the shock of hitting the water
or the sudden change of temperature.   Some fingerlings will die during
stocking.  But usually these are the weaker fish.  Careful handling will
mean less loss of fingerlings, as well as fry.

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Stocking Adult Fish.  Adult fish are a little more difficult to stock
than fry or fingerlings.  First, they are large (from 0.5kg up to
3.0kg) and can injure people and themselves by jumping out of containers
or ponds when they are being carried or caught.   For example, Chinese
carp often hurt themselves this way.   This problem is controlled by
placing a net of some kind on top of the container so they cannot jump
To move fish from one pond to
another, or from a pond to a container,
make a carrying cradle.
Use fishnet and pieces of wood or
bamboo for handles.  The cradle is
placed around the brood fish in
the water.  Then the fish can be
lifted out of the water and carried
to the new pond or to the container
for transporting.  There the cradle
is released and the brood fish
swims away.  Brood fish must never
be thrown into a pond.

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Adult fish often are nervous when being taken from one place to another.
Some pond owners even put a hand or a handkerchief over the fishes' eyes
when they are carried.  Care is necessary when handling, however:
brood fish particularly are sensitive
to being handled.  They bruise easily
if they are held tightly, and the
bruises can become sites for infection.

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Brood fish are often carried in tubs
or drums half-filled with clean, well-
oxygenated water when they must be
carried a long distance.  Change the
water often and check the water temperature
each time.  If the brood fish
are very active, mix a solution of 1
to 4 grams per liters of urethane in
the water.  This will make the fish
slow and less active, so they can
be moved without injury.
Routine Pond Management
After the ponds are stocked, ongoing management of the pond includes:
    *   feeding and fertilizing as necessary
    *   keeping the pond in good condition
    *   watching for trouble and disease
Each pond, whether it is small or large, one pond or one of several,
requires supervision in the above areas.   And good management requires
that checks of the condition of the fish and the pond be a regular
part of the pond owner's day.   Guidelines for both daily and monthly
general maintenance are given here.   Then, since fish in ponds are
treated somewhat differently depending upon their species, and their
stage in the life cycle, more detail on managing fry and fingerlings
and managing brood stock is given.
Ponds and the fish in them must be taken care of every day.  It is a
good idea to have the pond owner follow a checklist of things to do.
Daily care will greatly lessen the chance that something will go
wrong in the pond.
A good checklist might look like this:
    *   check the pond for leaks
    *   clean filters
    *   watch fish behavior near the feeding area
    *   feed the fish
    *   add fertilizer, if necessary
    *   watch for predators
IMPORTANT:  Check the ponds at the same time each day.  Early morning
is the best time because oxygen levels in the water are lowest then,
and the fish are more likely to have trouble at that time of day--if
they are going to have trouble at all.
Each step on the checklist involves certain activities and is discussed
in more detail here.
Checking for Leaks.  Check all walls, gates, inlets, and outlets.   It
is possible for a plug on a drainage pipe, for example, to work loose,
or partly loose, so that water leaks from the pond.   Walls made of
hard-packed earth can erode (wash away), especially after heavy rains.
Little leaks get larger quickly.   It is important to be sure the
farmer realizes that in a pond only 2m deep, for example, loss of
even part of the water can create problems for the fish.
Cleaning Filters.  Again, this is very important.  Any filters in the
pond must be removed and cleaned of silt, leaves, or other materials
that have collected in them.   A dirty filter at the outlet pipe
could slow down the drainage process.
Watch the Fish.  A farmer can tell much about his fish by watching
them carefully.  If they are swimming quickly and easily around the
pond, they are well.  If they are waiting near the surface, they are
likely to be hungry.  If they are gasping for breath at the surface
of the water, there is not enough oxygen and the farmer will know he
has to act quickly to aerate the water in the pond.
Feed the Fish.  Remember:  in some ponds it is not necessary to feed the
fish extra food.  The pond can be made rich enough to fill all the
food needs of the fish.  However, some ponds and some fish require supplemental
feeding.  And, sometimes, even a pond which has provided
enough food before has to have food added to it.
Supplementary foods are given by:
    *   spreading the food over the water's surface, as with
       bread crumbs and rice bran

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    *   placing food inside a floating bamboo or rope feeding
       ring (which is attached to the bottom of the pond)
    *   pressing food into dry pellets which float in the feeding
       ring or fall to the bottom under the ring

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                 Guidelines for Feeding Fish
Here are some good guidelines for feeding fish which might prove useful
to the farmer:
    *   Always feed the fish at the same time and in the same part
       of the pond.  The fish will learn where to go to get food.
       Then, when the fish come near the surface of the water, inside
       the feeding ring, for example, the farmer can see how
       well they are eating and growing.
    *   Do not overfeed.   Give only the amount of food the fish
       will take at one feeding.  Too much food will not get
       eaten, but will decay and, therefore, will use up valuable
       oxygen from the pond during the decaying process.
       The amount of food can be found by experience.  And of
       course, the younger the fish, the less food they will need.
       A farmer is wise to start with a smaller amount of a food.
       Then, if the fish seem to be waiting near the surface in
       the feeding area, he will know more food is required.
       There are more exact ways to determine how much food to feed
       the fish.   Most pond owners feed fish at the rate of 2 to
       5% of body weight per day.  Therefore, 100 fingerlings
       weighing 6g each (a total weight of 600g) would receive
       5% of 600g, or 30g of food a day.  One hundred fish of
       breeder size weighing 1kg each, (total weight 100kg) would
       require 5kg of food a day.
       Making such measures and calculations is not possible
       for many farmers.  Therefore, it is best that they know
       which foods to give, how to give them, and how to judge when
       the fish are or are not getting enough food.
    *   Feed fish only 6 days each week.   This will give the fish
       a chance to feed on whatever food remains in the pond.
       Too much food can clog the gills of fish, particularly
       those fish who eat only very fine particles of food.
    *   Do not feed fish for at least one day before harvesting
       or breeding them.  When the fish eat, they void (empty)
       the waste from their bodies into the water.  This happens
       even more when the fish are stressed.  The combination
       of food and wastes makes the water turbid and
       increases the stress that is already placed on fish by
       the breeding and harvesting processes.
    *   Feed the right kinds of foods.   Some fish will eat almost
       any of the foods mentioned in the section on "Preparing the
       Pond."  Other fish are not as easy to please.  The farmer
       will have to experiment with supplemental foods.  If he
       gives food one day and it is not eaten, he should stop
       that food and try another.  Again, if he starts with
       small amounts only, he is not likely to run into trouble.
       While it is a good idea to test those foods most available
       to a farmer, here are some guidelines to feeding a
       number of pond fish.
Common Carp
Common carp feed well on the natural food produced in the pond.  However,
pond owners often give common carp supplementary food, so the fish will
gain weight quickly.  Some good supplementary foods for common carp
are dried silkworm pupae, fish meal and clam meat.   However, these carp
will eat almost anything.  Suplementary foods such as these are not
necessary.  The best way to increase common carp growth rates is to
fertilize the pond well so that the pond produces a good supply of
natural food for the carp to eat.
Not much is known about the feeding habits of some of the tilapia,
for example, Tilapia nilotica.   Tilapia mossambica and Tilapia zillii
are used to control filamentous algae, which is a habitat for mosquito
larvae, thus the tilapia is used to help with malaria control.
Tilapia are hardy and accept many foods.   Most tilapia ponds can be
managed in much the same way as carp ponds.
Chinese Carp
Chinese carp fry eat plankton, so it is important that they be placed
in a well-fertilized pond with a good supply of natural food.  Fry
can be fed supplementary foods after a while.   These foods include
egg yolk which is strained through a cloth into the pond, soybean meal,
rice bran, and peanut cake.  Once the fingerlings get larger, they can
be fed like common carp.
Remember, however, that the small pond owner is likely to have Chinese
carp as part of a polyculture.   If the polyculture has been planned
wisely, the Chinese carp will not need to be fed extra food.
Indian Carp
Young fry of Indian carp, like all carps, feed on the plankton in the
pond.  Normally fish ponds in India are fertilized by draining the
pond and drying, then adding a fertilizer made of some animal manure
mixed with oil cake at the rate of 200 to 325 kg/ha.   This produces a
good bloom of plankton for the newly hatched fry.   However, it has
now been shown that the Indian carp prefer zooplankton, though sometimes
they are given supplementary foods.   After the fish reach fingerling
size, no supplementary food is given.
Note that in any pond, the fish can be kept healthy, well-fed and
growing well by making sure the pond is well-fertilized so that it
produces its own food.  As a general rule, it is better for most small
farmers to work at keeping their ponds well fertilized or to find
natural foods which can be added to the pond.   Most small farmers do not
have extra foods to share with fish, but they do have access to organic
fertilizer materials, such as manure.
Fertilize the Pond.  The section on "Preparing the Pond" discussed
kinds of fertilizer, so the farmer should already be familiar with
what fertilizers can be used in ponds.   Again, the right fertilizer
is a matter for experiment and experience.
The farmer has already used fertilizer before filling the pond.  Now
he must watch the water carefully each day.   If the healthy green
color of a fertile pond is not there or if the water has become
brown, fertilizer is needed.   Fertilizers are applied depending upon
what kind they are:  REMEMBER:  organic fertilizers do not provide
their nutrients right away; inorganic fertilizers work very quickly.
A farmer who uses mainly organic fertilizers would probably be wise
to keep some amount of inorganic fertilizer on hand for those times
when he needs the fertilizer to work quickly.
Fertilizers are added to the pond in a number of ways:
    *   Leaves, grass, and animal manure may be left in piles
       around the inside edges of the pond.  This is probably
       not a good way to fertilize in a hot, humid climate
       where the faster decay process would result in faster
       use of oxygen.
    *   Liquid manures and "soups" are dipped into the pond
       around the edges or in the deepest water.
    *   Powdered fertilizers (chicken manure, superphosphates)
       are broadcast (sprinkled) in a fine layer over the
       entire surface of the pond.

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    *   Some fertilizers are left on platforms in the pond.
       The platforms are submerged near the surface of the
       water and confined behind a screen.

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Watch for Predators.  Check the pond area for signs of snake holes,
rat burrows, eels, and strange fish which may have entered through
holes in an inlet screen for example.   Any of these can be very
dangerous in a fish pond, particularly to a pond containing fry or
small fingerlings.  Make sure fences which protect ponds from farm
animals who might eat grass off the walls or break down the walls of
the pond have no breaks in them.
Not each of these things will require much time each day.  But a good
pond manager will at least check each of these items daily.
Ponds which are managed well day by day will require little other
treatment.  However, the following things will probably require more
careful attention every month or so:
    *   Check the pond walls.   Cut grass which is too long or
       plant more, if necessary.
    *   Check the pond bottom.   If there is too much buildup of
       silt and organic matter, shovel or scoop this material

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    *   Check for and remove weeds or other growth which might be
       a problem at harvest time or when a net is used in the pond.
    *   Give the walls and inlet and outlet systems an especially
       careful check for leaks and for blockage.  Make sure the
       water can flow smoothly in and out of the pond, so that
       if water needs to be put in or taken out quickly, there
       will be no problem.
    *   Check the fertility and turbidity of the water.  Even a
       pond well-fertilized at the beginning may need more fertilizer
       after a month of operation.
    *   Check the fish carefully for signs of disease.  If all has
       gone well during the month--the fish have gained weight
       and their gills are a healthy red color--the chances are
       that all is well.  But the fish should be checked especially
       carefully for signs of disease each month.  (See "Problems
       of Fish Cultured in Ponds.")  It does not take long for a
       disease to infect an entire pond full of fish.

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    *   Add lime if needed.   If the farmer has been adding
       fertilizer and feeding his fish regularly, but the
       fish still do not seem to be gaining weight well or
       moving in the water well, the water quality may
       need adjusting.
Good management is a key to a good fish harvest.   It is important for
the farmer to realize this and to work fish management into his
daily schedule.  But this is not always easy for him to do.  In many
parts of the world, farmers let their animals manage themselves, i.e.,
find their own food, etc.  This will not usually work with a fish
pond.  Fish cannot be put into ponds, left alone, and expected to
grow and provide food and income.   Successful fish pond operation requires
active attention by the farmer.
The management guidelines just described apply to all fish ponds,
regardless of type of fish or stage of growth.   There are, however,
some differences between managing a fry or fingerling pond and managing
brood stock.  So these differences should be looked at more closely
Management of Fry and Fingerlings
There are several ways to get fry.   If the farmer is breeding fish,
then he will have his own source of fry to bring to the rearing ponds
from the smaller nursery (hatching) ponds.   If the farmer has a small
backyard pond, where he raises fish from fry or fingerlings to market
size, he either gets his young fish from a market or another farmer
or scoops them out of natural waters.

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Wherever the young fish come from,
it is important for a pond owner to
know how many fry or fingerlings he
is putting into his pond.  If the
owner knows how many fish are going
into the pond he will know at harvest
time how many fish died (the
mortality rate) before they were
ready for harvest.  This information
can help the farmer make decisions about his management of the pond.
If, for example, more than half of the fish in a pond died between
the time they were put in as fry and the time of harvesting for
market, too many fish are dying; the farmer ought to find the reasons
why before he begins again.

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Fry are very delicate and must be handled gently.   Here is one way of
counting them:
    *   Take a basin or tub of which you know the size (50-100 liters)
    *   Put all the fry into this basin.
    *   Scoop up fry into a 200-250ml measuring cup.
    *   Count the fry in the measuring cup by slowly and gently
       pouring the fish back into the basin.
    *   Estimate the total number of fry in the basin by setting up
       a ratio like this.
           number of fry in measuring cup   =    volume of measuring cup
           number of fry in basin (total)   =    volume of basin
       For example, a measuring cup of 250 ml holds 100 fry.  Therefore,
       it is estimated, using this formula, that a 50 l basin full of
       fry holds 20,000 fry.
Here is another way of counting fry which is somewhat easier because
it does not depend upon cups and basins of any particular size.
    *   Put all the fry into an old container--an old metal garbage
       can, an oil drum, a washtub.
    *   Get an old milk can, or some other smaller container, and
       make sure one end is cut off.
    *   Fill the smaller container with strained water.
    *   Mark a line on the garbage can to show the level of water
       being put in.
    *   Fill the milk can and pour the water into the larger can.
    *   Continue to fill the smaller can and dump water from it into
       the larger can.
    *   Count how many small cans of water it took to fill the larger
       can as high as the line drawn on the can.
    *   Fill the smaller can with fry and count them carefully.
    *   Estimate the number of fry by multiplying the number of fry
       in the milk can by the number of cans it takes to fill the
       large container to the line marked on it.
       Therefore, if there were 50 fry in one milk can, and it takes
       25 cans to fill the larger container to the mark, there are
       50 x 25 or 1,250 fry.
Fingerlings are easier to count than fry because they are older and
larger.  The same kind of measuring system could be set up.  But the
containers would have to be able to deal with the larger fish.  A
farmer who has raised his fingerlings from fry should count the fingerlings
as he sells them or moves them from a nursery pond to a rearing
pond.  Then he will know how many survived.  If a farmer started
with 20,000 fry and had 15,000 fingerlings, 5,000 fry died.  But this
is a death rate of only 25%--which is not a terribly high figure.
Again, the farmer must accept that some of his fish are going to die.
A pond owner who raises fish is more likely to be able to handle fry
successfully.  Fry are very delicate and must be protected carefully
from predators and sudden temperature and oxygen changes.  The fry
hatch from their eggs in 12 to 72 hours depending upon the temperature
and the type of fish.  The fry then live off the yolk sac which is
attached to them.  This sac lasts several days.  But then the farmer
must be sure that the water provides enough food for the fry.
Many pond owners feed the fry with the yolk of a hard-boiled chicken
egg that has been strained through a cloth with water.   After a few
days of this, the fry can begin to eat the phytoplankton and the
zooplankton in the pond.  Make sure that there is always enough food
for the fry to eat before you transfer the fry to the rearing pond.
For a farmer who has only one new pond, it is probably a better idea
for him to start with young fingerlings.   This will give more chance
of success than starting with fry.
This is not to say that a farmer who has only one pond cannot start
his fish crop from eggs or fry.   He can.  One way this can be done is
to keep the eggs in a washtub or large container rather than a pond.
The eggs must have plenty of oxygen, so the water must be changed often.
Any unfertilized eggs must be removed so that they do not cause infections
in the fertilized eggs.  Unfertilized eggs are white; fertilized
eggs are yellowish red.
Keeping fry in a smaller container is a good idea because it allows
the farmer to better control the surroundings.   Fry often get
bacterial and fungal infections and are a favorite target of birds.
Again, the water must be kept rich in oxygen and food which can be
eaten by fry.
The care of eggs and fry is very difficult and very important.  A
farmer who wishes to breed fish must certainly work to gain experience
handling delicate eggs and fry.   A farmer who wants only a food source
in his backyard may wish to take the easier road and start with
The size of fingerlings depends upon climate, water temperature, food
given, and the number of fish stocked in the pond.   The following are
some average sizes and weights common in the Philippines:
                                        Average         Average
                                        Lengths         Weights
Milkfish                                 6.57cm          2.9 grams
Tilapia                                  6.33cm         5.8 grams
                                        5.64cm          5.6 grams
Silver Carp                              7.39cm          7.1 grams
Common Carp                              7.39cm          7.1 grams
Fingerlings may be fed supplementary food if it is necessary.  Remember
that fish usually receive supplementary food which is about 5%
of their body weight per day.   This was discussed in more detail in
the section on preparing the pond, so there is no need to go into
detail here.
It probably is a good idea, however, to note again that farmers should
proceed slowly when giving supplementary foods.   Add only small amounts
of food and watch the fish carefully to see how they accept it.  And
the most important thing is to make sure the pond is producing enough
of its own food.

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If the guidelines for management, discussed earlier in this section,
are followed, the fingerlings should grow well.   When the fish reach
a good size (the size preferred in the farmer's area -- some people
like smaller, rather than larger fish), they can be harvested and
A well-cared-for fence protects
this farmer's pond from unwelcome

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Breeding is the term used to describe the complete reproductive cycle of
fish.  Successful breeding depends on the health of the brood stock and
the ability of the fish to spawn.   Spawning describes the actual release
of eggs and sperm by the adult fish, and the fertilization of the eggs
by the sperm.  This section gives information concerning the breeding of
pond fish.
Management of Brood Stock
A brood fish is a fish that has reached its full growth and is able to reproduce.
The age at which this happens depends upon the kind of fish, the
climate, the quality and amount of food.   The specific characteristics of
brood fish are basically the same for every fish species.  In general,
good brood fish are:
    *   well-formed and unbruised
    *   free of parasites and disease
    *   lively and active
    *   a few years old, between 0.5kg and 3.0kg (depending upon species)
    *   sexually mature (so they can be separated by sex)

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Other characteristics used in choosing good brood stock are relative size
and the large, rounded abdomen in the female fish.
Choosing brood stock of common carp is more difficult.   The characteristics
of these fish are:
    *   moderately soft body
    *   broad and flat lower side of belly, so that the fish
       can stand on its belly
    *   relatively great body depth compared to length
    *  broad, but supple, caudal peduncle
    *   small head and pointed nose
    *   rather large and regularly inserted scales
    *   genital opening nearer to the caudal peduncle than in the
       average carp
In general, the larger the female carp, the more eggs it will produce.
A carp of 45-50cm can produce up to 310,000 eggs; a carp of 60-65cm produces
up to 1,507,000 eggs at one time.   But older carp (5 years and up)
will have eggs that are not as healthy as those of younger carp (2 years
old), so size is not the only factor in choosing good breeders.  Good
breeders usually are younger fish weighing 1 to 2 kg.
Brood fish can be obtained from natural waters by seining (netting) or
traps, from fish dealers or fishermen, from other pond owners, or from
government fish farms.  Select more males than females, so that when a
female is ready to spawn, at least one male also will be ready.
The numbers of breeders needed depends upon the size of the brood pond.
For example, a carp weighing 1 kg needs about [5m.sup.2] to live and spawn.
Therefore, a brood pond of 0.5 ha (5,000 [m.sup.2]), will hold 1,000 brood fish
of an average I kg weight.  Most brood ponds are much smaller than this,
however, so the farmer must calculate the number of fish to place inside.
After some experience, the farmer will be able to judge the correct
numbers for his pond quite easily.
After choosing the breeders, treat them for possible parasites or
disease before placing them into the brood ponds.   This treatment is done
by placing the fish, one by one, into a bath of 10 ppm of potassium
permanganate for 1 hour, them transferring them to a bath of 15 ppm of
formalin for another 4 to 12 hours.   These mixtures can be prepared in
washtubs.  After the fish are treated, they can be placed into the pond.
Of course, brood fish coming from a source which is known to be uncontaminated
and free from disease would not require this treatment.
(Further information on treating fish for disease is found in "Problems
of Fish in Ponds.")
The brood stock must be well cared for.   If they are in good health, the
eggs will be healthier.  It is probably more important to feed brood
stock with supplementary foods than it is to give supplementary food
to fish at any other stage of growth.   Feed them rice bran, so bean
cakes, or other processed foods at a rate of 5% of body weight per
day.  They should be managed carefully according to the general guidelines
discussed earlier.  Remember:  brood stock should not be fed for
at least one day before they are caught for breeding.
When caught by net, examine the brood stock carefully and handle them as
little as possible.  Use a cradle to handle and carry the fish from one
pond to another.  They should be carried to a spawning pond, stocked in
the proper manner, and left to spawn.   After spawning has occurred, the
brood fish should be caught again and carefully carried back and released
into their brood pond.
Always remember to treat brood stock well, and never select a fish for
spawning which does not show the proper signs of readiness to spawn.
(See the following information on spawning behavior.)
Spawning in fish ponds is done in two ways:
    *   Natural spawning -- the fish are placed in ponds and left
                           to spawn by themselves
    *   Induced spawning (artificial propagation) -- methods used
                           by man to make (induce) the fish release
                           their eggs and sperm
Both of these spawning methods have advantages and disadvantages.
Natural Spawning.  Fish who spawn naturally require only a well-prepared
brood pond.  Use a net to seine the pond and choose good breeders.   Then
introduce them into the spawning pond.   Most fish will spawn the first
night in the new pond; if they do not spawn, then leave them alone for
a few more days.  If they still do not spawn, remove them and start
again with some other breeders.
Each fish used in pond culture has very definite and very different needs
to spawn naturally in ponds.   To encourage spawning, ponds can be prepared
differently depending upon the fish.   Therefore, the best way to
prepare is to understand how that fish would spawn in nature.  The
following describes the natural spawning behavior -- in nature and in
ponds -- of some of the more common pond fish.
THE COMMON CARP -- Spawning in Nature
In China, common carp spawn in the rainy season when the water level and
temperature rise at the same time.   This rise in temperature and water
level is a signal to the carp to begin maturing sexually.   When they are
fully mature (ripe), they begin their mating behavior, which includes
chasing each other in and out of the plants floating on the water surface.
The farmer who sees his common carp doing this has a good indicator that
his fish are ready to spawn.
When common carp are ready to spawn, the female carp begins to swim in
and out of the plants.  She then releases her eggs on the plant roots.
The male follows her very closely.   As she releases her eggs, he releases
his sperm (milt); the sperm fertilizes the eggs.   Carp eggs are slightly
sticky (adhesive) and they stick onto the plant roots just under the
water surface until they hatch.   Depending on the temperature of the
water, the eggs hatch in 2 to 6 days.

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The new common carp fry feed off of their yolk sacs for another 2 to 6
days, until it is absorbed, and then begin to feed on the zooplankton
in the pond water.  The carp can spawn all year round in nature, as long
as the water temperatures stay high, because a carp is capable of
breeding once every two or three months.

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THE COMMON CARP -- Spawning in Ponds
The best way to spawn common carp in fish ponds is to try and reproduce
the natural conditions of high water levels and temperature.  First the
fish are taken from a cool pond and put into a pond with warmer water.
Then the water level in the pond is increased.   This provides the
signal for the carp to mature sexually.   When the fish mature, place
egg collectors, called kakabans, in the pond, or just some water plants
with roots that hang down.
After the introduction of the kakabans, the female fish begin to investigate
the fibers.  Soon the females will begin spawning behavior and the
fish will spawn on the fibers of the kakaban.   Because the eggs are
sticky, they stick to the kakaban, and the entire kakaban can be lifted
and transferred from the breeding pond to the nursery pond.
Important:  Common carp are omnivorous; that is, they eat anything --
including their own fry.  It is best to transfer the full kakabans to
another pond for hatching.
A kakaban is a floating mat that uses a fiber like inkjuk, or beaten palm
bark or leaves that have been shredded into long fibers.  These fibers
are bunched together and tied in the middle.   The bundles are then nailed
down between two long pieces of wood or bamboo and floated just under the
water surface, with the ends hanging down into the water.  This will
look like the roots of water plants to the fish.

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A kakaban is better to use for carp breeding than plants because it can be
boiled and sterilized each time it is used.   This will prevent any fungus
or bacteria from attacking the newly-laid eggs.
TILAPIA -- Spawning in Nature
Tilapia spawn every month or so, as long as the water is warm.  The male
begins the reproductive behavior by digging holes in the pond bottom
or side wall about 35cm across and 6cm deep.

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The female will deposit her eggs, about 75 to 200 of them, in the nest,
and then the male releases his milt.   The female picks up the eggs and
the milt in her mouth, so the fertilization of the eggs of actually takes
place in the females' mouth.   Tilapia often are called "mouth breeders."
The eggs remain in the female's mouth until they hatch -- 3 to 5 days.
Then the fry stay in the female's mouth until the yolk sac is gone.
During this time, the female does not eat.
As the fry grow, they continue to hide in the mother's mouth when they
are threatened.  The main reason for this mouth-breeding is for protection
of the young fish, since the tilapia have relatively few eggs
compared to some other pond fish.   Tilapia is also a favorite food for
a number of predators.  Because the fry are so well taken care of by the
mother (and even sometimes by the father fish), these young fish are
easier to raise than some other species of fry.

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TILAPIA -- Spawning in Ponds
Tilapia spawn well in ponds.   It takes no special equipment or ponds.
A tilapia needs only a pond with a loose bottom to spawn.  The spawning
ponds can be stocked with 25-30 females per [100m.sup.2] (1/100 ha) and about
40-45 males.  If the temperature is warm enough, the males will begin
digging holes in the pond bottom immediately, and the female will be
attracted to the hole and release her eggs.   From that point, spawning
continues as in nature.

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Tilapia will also spawn in ponds that do not have loose bottoms.  In
these ponds, place large-mouth pottery jars or wooden boxes on their
sides on the pond bottom; the tilapia will use these containers as nests.
Young tilapia mature at about 3 months, when they are only 6 to 10cm
long.  They can then breed every 3 to 6 weeks, as long as the water is
warm.  In areas near the equator where the water is always warm, tilapia
can breed almost continuously.
When a fish begins to breed, his energy goes into the development of his
reproductive organs, not into bodily growth.   The main problem with
breeding tilapia in fish ponds, therefore, is the rapid reproduction of
this fish.  Reproduction can be controlled by sorting the tilapia by sex
and placing them into separate ponds, or by producing a monosex culture
by hybrid crossing.  However, these methods can usually be done only by
large commercial or government hatcheries where conditions are controlled.
The problem of fast breeding in tilapia ponds can also be controlled by
using some natural predators of tilapia in the pond.   The predators most
often used are catfishes of the genus Clarias and, sometimes, eels like
Anguilla japonica, and some other carnivorous fishes like Serranochromis
robustus, in a polyculture with tilapia that are reproducing.  These
predators will eat the young fry, allowing the adult fish to continue
their growth by having no competition for the available food.
CHINESE CARP -- Spawning in Nature
Chinese carp spawn in the large rivers of China when the spring rains
cause the water levels of the river to rise.   The eggs are found
drifting down the rivers with the current, and they are collected by
fry dealers as they drift.  The main requirements for hatching Chinese
carp eggs are a swift current and plenty of oxygen.   Not much is
known about their breeding habits in nature, but they are likely to
show normal chasing behavior and then spawn, like common carp.  Most
Chinese carp are cultured by collecting their fry and eggs from the
rivers in the spawning season.

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CHINESE CARP -- Spawning in Ponds
The Chinese carp are all annual breeders.   Good brood stock is chosen
in the same way as breeders of common carp.   Chinese carp breeders
usually are kept in small ponds, separated by sex.   When they are
sexually mature, it is quite easy to tell them apart, since the males
will usually leak milt when handled, and develop other body changes such
as serrations (rough edges) on their fins.

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Chinese carp brood stock must be well cared for, like all brood stock.
They must be allowed to live undisturbed until time for spawning.  However,
the Chinese carp must be induced to spawn (see Induced Spawning).

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INDIAN CARP -- Spawning in Nature
The Indian major carp will not spawn in standing water, so special ponds
are built in India to provide a flow of water for these fish.  These
ponds are built like barrage ponds in upland areas so that the water
flows through them.  But these ponds are impossible to build in many
locations, so the Indian carp often are bred by induced spawning.
In nature, the Indian carp spawn in rivers like the Chinese carp.  The
eggs are then collected and transferred to hatching ponds.

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INDIAN CARP -- Spawning in Ponds
Good Indian carp breeders are sexually mature when milt comes from the
male as it is pressed on the stomach.   Ripe females have soft, rounded
bulging abdomens and reddish genital openings.   The breeders should
be kept separated by sex in ponds prior to the breeding season, so that
they will readily spawn when introduced into the breeding hapas.
Usually one female is placed into a hapa with two males to insure that
fertilization occurs.  If a farmer can place the breeding hapa into
a source of flowing water, he may be able to breed these fish naturally.
If not, Indian carp must be bred with induced spawning methods.
A hapa is a rectangular box about 1m in depth and 1.6 - [6.5m.sup.2] in surface
area.  It can be made from mosquito netting with a mesh size of
3mm.  Hapas can be made in many sizes.  Some other dimensions of hapas
used in Indian carp culture are:
                      91cm x  91cm x 183cm
                      91cm x 122cm x 244cm
                      91cm x 152cm x 305cm
                      91cm x 183cm x 366cm

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The hapa is held in place inside the 'pond with stakes of bamboo or other
wood.  The breeders are put inside the hapa.  Kakabans are placed below
the water surface, and the top of the hapa is closed so that the
breeders do not escape while mating.   After spawning, the kakabans can
be removed and taken to the nursery pond and the breeders released into
the pond.  Hapas can be used to spawn other fish as well.
THE GOURAMI -- Spawning in Nature and Ponds
The gourami build nests out of plant materials to lay their eggs.  The
eggs hatch in about 30 hours.   The fry float belly-up for 5 days until
feeding begins.  The gourami can spawn all year round in warm water

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This is a very good pond fish, and very easy to breed as long as you
have a well-fed brood stock.   The natural food of the gourami is soft
leaves of plants like Colocasia and Carica.   They can also be fed rice
bran before breeding.  Usually 10 females and 5 males are stocked in
ponds as small as [100m.sup.2] and the eggs float until they hatch.
Breeding in ponds is done by merely placing the breeders together in a
pond where there are some marginal plants available for nest building.
Once the fry hatch and begin to feed, they can be stocked in nursery
OTHER GOURAMIS -- Spawning in Nature and Ponds
The snakeskin gourami and the three spot gourami build nests made of air
bubbles so that their eggs float.   The kissing gourami scatters its eggs,
which are free-floating.

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To breed the snakeskin and three spot gourami, place the ripe fish into
a well-oxygenated pond that has a good growth of aquatic vegetation,
particularly Hydrilla verticillata.   These fish will continue to spawn
as long as the water temperature stays at 26 - 28 [degrees] C.  Hatching takes
place about 2 days after spawning, and the fry absorb the yolk sac
within 3 to 7 days.
The kissing gourami spawn at 6-month intervals and spawn within 18 hours
of stocking in the pond.  Some of the eggs may be eaten by the parent
fish, so there must always be abundant vegetation in the spawning pond
to prevent this.  The eggs hatch in 2 days and float on the surface for
3 to 4 days.  The new fry eat the decaying plants and plankton in the
CLARIAS CATFISH -- Spawning in Nature and Ponds
Clarias macrocephalus spawns during the rainy season in nests on the
bottom of natural waterways, while Clarias batrachus spawns in horizontal
holes in the banks.  Hatching takes place after 20 hours at 25 - 32 [degrees] C.
The fry are then collected by hand net from the nests.   There are
2,000 to 15,000 fry in each nest.
Clarias catfish will spawn naturally in ponds, but induced spawning
methods may be used if necessary.

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THE TAWES -- Spawning in Nature and Ponds
The tawes spawn in the rainy season.   Tawes ponds usually are about
200 to [500m.sup.2] and about 50cm deep.   The ponds should be dried for 5
days before they are filled, and the spawners should be introduced when
the pond is half full.  Tawes need well-oxygenated water that has a strong
current to spawn.  Mating occurs at night; then the current should be
turned off and the eggs spread out evenly on the pond bottom.  The eggs
hatch in two to three days.  After 20 days, the fry can withstand the
current, and it should be turned on again.   Tawes females produce
about 20,000 fry each.

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HETEROTIS NILOTICUS -- Spawning in Nature and Ponds
This species is normally light-colored, but during the breeding season
it changes to dark brown.  The spawning of Heterotis niloticus in
nature begins at the end of the dry season when water is very warm.
The fish splash in the shallow water among the weeds in the ponds to
begin their breeding behavior.   Then the male builds a nest of weeds
in water that is 10 - 45cm deep.   The nest is made in a depression
that is 15cm deep and 60 - 100cm wide.   The nest has a grass wall at
its outer edge which keeps other fish out of the nest.   To get in and
out of the nest, Heterotis niloticus jumps over this wall.

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The eggs of Heterotis are about 3mm in diameter, and are laid in the
bottom of the nest and then fertilized.   One of the parent fish is
always in the nest to circulate water over the eggs (to give them
oxygen).  The eggs hatch in 4 - 5 days.  The fry travel in a "school"
and stay with their parent fish for several months after hatching.
The fry are very delicate, and should not be handled for a while.
EELS -- Spawning in Nature and Ponds
The eels used in Taiwan (Anguilla japonica) spawn in the sea, and
the fry (called elvers) swim upstream where they are collected by dealers.
Eels, are stocked in rates of up to 25,000 fry/ha along with other fishes,
and must be fed supplementary feeds like pellets of trash fish.  It is
not recommended that a beginner work with eels because they must be fed
protein and are not very efficient converters of food.
Eels cannot be bred in ponds.

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MILKFISH -- Spawning in Nature and Ponds
Milkfish spawn in saltwater during the rainy season.   The fry are caught
along the shore line at breeding season (which corresponds to the
rainy season) and then transferred and acclimatized to freshwater ponds.
This is done for the most part in the Philippines and in some other
Southeast Asian countries like Indonesia and Taiwan.
Milkfish cannot be bred in ponds.

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STRIPED MULLET -- Spawning in Nature and Ponds
The striped mullet is a saltwater fish, and spawns in the sea.  The
fry are collected as they swim upstream.
The mullet can be induced to spawn by hormone injection, but this is
very difficult and certainly is not recommended for a small fish pond
Induced Spawning.  Induced spawning means making the fish produce eggs
an milt when they will not do so naturally.   Induced spawning is done
when the pond conditions cannot be made to encourage natural spawning,
or when the fish are not ready to spawn when the farmer wants them to
Spawning can be done by three methods:
    *   hormone injection
    *   hormone injection with stripping
    *   stripping
Each of these methods has advantages and disadvantages.
Hormone Injection.  Hormone injection is the most common method of
induced spawning, and it requires certain kinds of equipment:
    *   hypodermic needle and syringe
    *   mortar and pestle
    *   saline solution or distilled water
    *   centrifuge
    *   test tubes
    *   dissecting kit

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This technique uses the pituitary gland (the hypophysis) of the fish.
This gland contains the substances(hormones) that trigger the reproductive
organs of the fish to start developing.   When these hormones are
taken from a ripe fish and injected into a fish that is ripe, but has
been unable to spawn, the injected fish will spawn in 6 - 12 hours.
The ripe fish must be killed to get the pituitary gland out.  This must
be done very carefully.  The gland is very small:  less than 1mm in
diameter in the common carp, which has a relatively large pituitary.
The pituitary gland is a round, yellowish-red organ located in the brain
pan of the fish.  Here is the method commonly used to take the gland
from the fish:
    *   Use a mallet or dull knife.
    *   Hold the fish near the head with one hand.
    *   Hit the fish above the eyes at the point where the skull begins.
       This will kill the fish.
    *   Make sure to hit straight and up a little.  A solid hit should
       dislodge the skull.
    *   Slit the skin around the front and sides of the skull, then lift
       up the top of the skull and fold it back as if it were a hinge.
       The brain is attached to the top of the skull; by folding it back,
       the underside of the brain is exposed.  The pituitary gland is located
       in the middle part of the underside of the brain.
If located in this way, the pituitary gland is relatively easy to
find.  However, this must be done carefully.  If the skin is cut too
much, or the fish is handled too much, the contents of the brain will
move and the pituitary will be hard to locate.   The brain contains a
number of fat deposits which are yellowish and could easily be confused
with a pituitary by someone who was not familiar with that gland.
Most farmers will not be interested in doing hormone injection spawning.
But you should be familiar with and be able to do it.   Steps for
processing the pituitary gland and giving the injection are given below:
    *   Select the fish you want to spawn and weigh them.
    *   Select the fish that will be killed for their glands and weigh
       them.   Always match the weights of the donor and recipient
       fish.   If a donor is 1.5kg and the recipient is 3kg, use pituitaries
       from two 1.5kg donors.
    *   Kill the fish, as outlined above.
    *   Remove the pituitary from the fish matching weights (or use
       2 to 3mg of dried pituitary gland for every kilogram of body
    *   Place the pituitary gland into the mortar.
    *   Grind the pituitary with pestle until it is a pulpy mass.
    *   Wash the pituitary into a test tube with 1 milliliter distilled
       water or saline solution.
    *   Place the test tubes into the centrifuge.
    *   Centrifuge the glands for 5 minutes.
    *   Remove the test tubes from the centrifuge.
    *   Draw up the liquid portion from the test tube into the
       hypodermic needle, leaving the pulp of the gland in the
       bottom of the test tube.

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    *   Inject the fish above the lateral line behind the
       dorsal fin, just underneath the scale.
    *   Place breeders into the breeding pond.
All of the materials used in hypophysation can be found or made
easily.  A simple centrifuge can be constructed very easily from a
hand drill (see next page for instructions).   If a centrifuge cannot
be found or made, the fish may be injected with a whole pituary gland.
The gland may be dropped into the syringe, water added, and injected
into the fish as outlined above.   The force needed to push the gland
out through the needle will crush the gland as if it were being ground
with the mortar and pestle, and this will allow the hormones to be
After the injection, the female fish will begin to develop her eggs
until they are ready for fertilization by the male.   In some fish, it
is necessary to inject the female twice with varying amounts of
pituitary extract (see Chinese carp) and the male, once.  After the
injections, the fish are treated in the same way as in natural
                      MAKING A CENTRIFUGE
Tools and Materials:
    *   1 hand drill
    *   1 20cm piece small wood (or bamboo) dowel rod
    *   2 metal cigar tubes (or plastic, or rubber hose with clamps)
    *   2 pieces medium wire (long enough to wind around the tubes 6
       or 7 times)
    *   1 piece heavy wire about 9cm long (old coat hanger will work)
       cotton balls or pieces of soft material
    *   2 test tubes or small clean glass bottles
    *   string, tape, and nylon fishing line

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Construction Steps:
    *   Drill hole through one end of dowel rod about 1cm from the
    *   Remove drill bit from drill.
    *   Insert dowel rod into drill bit hole, leaving end with newly
       drilled hole at opposite end on top.
    *   Insert piece of heavy wire through the hole in dowel rod.
    *   Bend the ends of the wire into loops.
    *   Secure the wire on either side of the dowel rod with tape
       to keep the wire from slipping through the dowel rod hole.
    *   Wind medium wire around each cigar tube leaving about 2.5cm
       of wire free at the top of each tube.
    *   Attach tubes to heavy wire by bending medium wire (left
       over from step just completed).
    *   Place a small cotton ball in the bottom of each tube to
       cushion the test tubes.
Stripping.  Stripping is the term given to the method of actually
pushing eggs and sperm out of the fish and mixing them in a dish.  This
can be dangerous to the fish, mostly because the fish can be hurt by
pressing on the belly.  Stripping is especially dangerous to a fish which
is not ready to spawn.  If the fish is ready to spawn, a gentle stroking
motion down the side of the fish towards the genital opening will be
enough to release the eggs or sperm.

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First the eggs are stripped into a dry dish.   Then the milt is stripped
into the same dish.  Mix the eggs and milt gently with a feather.   Add
water to the dish so that fertilization can occur.   After a few hours
and a few changes of water in the dish (to provide eggs with oxyqen),
transfer the fertilized eggs to the kakabans and allow them to hatch
as normal.
There are other variations of stripping that are worse than the one
outlined above.  One method involves killing the female or male, or
both, and removing their reproductive organs and then mixing the eggs
and sperm by hand.  Not only is it necessary to kill both breeders, but
if the eggs and sperm are not ripe (mature) and ready for fertilization,
no fry will hatch.
Stripping with Injection.  Often stripping is done after the fish have
been injected with hormone extract.   The fish are injected, and the
eggs are allowed to develop.   Then the fish are stripped into a dry
dish, etc.  Stripping with injections works fairly well.  But of the
three methods of induced spawning described here, the best is just
to inject the fish and let them spawn by themselves in the pond.  The
following paragraphs give directions for induced spawning of some
important pond fish.
The Chinese carp must be induced to spawn by hormone injection.  The
normal dosages for bighead, black, mud, and silver carp are 2 to 3mg
of dried pituitary or 3 fresh pituitary glands for every kilogram of
female fish.  That is, if the female silver carp weighs 2.5kg, 5mg of
dry pituitary or 6 fresh pituitary glands are needed to ripen her eggs.
Or HCG (human chorionic gonadotropin) can be used at dosages of 700 to
1000 IU (international units) per kilogram.   But HCG is expensive and
certainly not available to everyone.   Grass carp need higher dosages
(3 to 4mg dried pituitary per kilogram of body weight).   Inject only
a fraction (1/10 to 1/4) of the total for the first dose; then, follow
it with the rest of the dose, 6 - 24 hours later.
After injection, put the breeders into the breeding pond.  The temperature
should be about 23 - 29 [degrees] C to encourage spawning, and the oxygen
content should be at least 4ppm.   It is best to put in two males for
every female.  Let the fish spawn on their own; they will spawn within
a day.  Remove the breeders after spawning.
Hatching Chinese carp is complicated.   Chinese carp eggs need a constant
supply of clean, well-oxygenated water flowing from the bottom up
through the eggs to stimulate hatching.   Some types of hatching
bags have been developed for this purpose.   One kind of bag hangs from a
rack down into the nursery pond or a trough, and water is bubbled up by
pipes from the inflow pipe.  These bags have an advantage in that once
the fry are hatched, they can easily be transferred without touching
them at all.  This is good, because Chinese carp fry are very sensitive
to handling stress.

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After the carp spawn, the eggs are collected by net or by draining
the breeding pond, and they are placed in the hatching bags (or
shallow trays) as soon as they have hardened after ferlization (1 to
2 hours).  The eggs hatch in 1 - 2 days depending on the temperature,
and then absorb their yolk sacs in another 3 - 6 days.
As soon as the fry absorb their yolk sacs, they should be transferred
in the hatching bags to nursery ponds.   The nursery ponds should be 0.5
to 1.0m in depth and the oxygen level should be at least 4ppm for good
fry growth.
The spawning of Chinese carp is a very complicated business and is usually
done inside carp hatcheries so that all conditions can be controlled.
In China, the carp hatcheries sell their fry to fish pond owners who
then raise them to marketable size.   For most farmers, common carp is
a much easier fish to work with and is just as valuable for food as
are Chinese carp.
The Clarias macrocephalus fishes are injected with pituitary extract at
a rate of 13 to 26mg/kg at 25 - 32 [degrees] C.   Spawning occurs within 16 hours.
Larvae (fry) absorb the yolk sac in 5 days, and are transferred and reared
in ponds only 18cm deep.  The best food for fry is zooplankton, but
after 2 to 3 weeks, trash fish may be added.   They can be fed rice bran
as well, and later on a mixture of trash fish, rice bran, and broken
ice.  In Thailand this sort of production gives yields of 97,000 kg/ha
per year.  Clarias catfish are used in fish ponds throughout Southeast
Asia now, and are enjoyed for their good taste.
If you cannot build a fish pond like a barrage pond or spawn the Indian
carp naturally in ponds, they can also be induced to spawn by hormone
injection but this is very difficult to do.   Induced spawning is
dependent on the dosage and the stage of maturity of   the breeders.
Breeders should be about 2 to 4 years old, and weigh 1.5 to 5.0 kg.
Females are injected twice, once with 2 to 3 mg of pituitary gland per
kg body weight, and then, after 6 hours, with 5 to 8 mg/kg.  Males
are injected once, at the time females get their second dose, with a
dose that is equal to the first dose given to the females.  After
the second injection, the fish are placed together in breeding "hapas"
and spawning takes place within 3 to 6 hours.   The breeders are put
inside the hapa, kakabans are placed below the water surface, and the
top of the hapa is closed so that the breeders do not escape while
mating.  After spawning the kakabans can be removed and the breeders
released into the pond.  The eggs should be transferred to deep
hatching hapas where they will hatch in 15 to 18 hours at 27 [degrees] C.
However, this induced breeding does not work as well as Chinese carp
breeding, so most Indian carp fry are still caught and collected
in natural waters.
Sometimes common carp will not spawn in ponds, and they are injected.
The amounts needed for common carp are determined by the fishes' weight.
Usually the common carp is injected only once with pituitary extract
from a fish that has the same weight as the injected fish.  The male
is not injected.  After the injection, the fish are placed into the
breeding pond.  Usually a good female breeder will weigh 1 to 2 kg.
This one large female is placed with 1 or 2 males, so that the
total weight of the males is approximately the weight of the female.
If you have a female of 2 kg, you can use two males of 1kg each.
The more males, the greater the chance that fertilization will occur.
If you have a large breeding pond, you can place about 5 or 6 large
female fish and 10-15 males to insure that all the eggs are fertilized.
Carp will only respond to pituitary injections from other carp.  However,
many other fish will respond to the pituitary gland of common carp, so
often carp are kept just to serve as donors of this gland in other
induced spawning attempts.  Also, carp glands are relatively large
and easy to find, compared to the glands of other fishes, and can be
stored for later use by drying, freezing, or powdering.   Carp glands
can be preserved by placing them in 100% dry acetone, then cooling
them by placing that jar they are placed in, into an ice bath.  Every
12 hours, the acetone should be changed, for a total of four times.
Then the pituitaries are air-dried, and stored in an air-tight
container.  This is called the alcohol drying method; glands preserved
in this way can still be used after 10 years!
7           Harvesting Fish
Harvesting is the collection of fish from a pond for sale at market,
or for cooking and preservation for family use.   Harvesting can refer
to collecting all the fish or to taking out only some of the fish
(this happens often in tilapia ponds having both young and adult fish).
If the pond can be drained, harvest the fish by draining the pond into
the catch basin and collecting the fish with a scoop net.  If the pond
cannot be drained, drain out as much water as possible and use a series
of nets to catch the fish.
Types of Nets
There are different kinds of nets which can be used in ponds.  Some nets,
such as the one shown here are gill nets.   Gill nets often have mesh
sizes from 2-3cm; they are often used to harvest the largest fish in a
pond and leave the smaller fish until they grow larger.

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They are called gill nets because the
fish pokes his head through the net
mesh, and is caught around the gills as
he tries to wiggle through the net.
Another net used to harvest fish is the seine.   A seine can collect all
the fish in the pond at one time because it has smaller openings (mesh
size) than the gill nets, and it is usually made of heavier fibers to
hold the fish.  (See the end of this section for instructions on making
a seine.)

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Both seines and gill nets have lead sinkers (weights) attached to the
bottom ropes.  These weights hold the nets at the bottom of the pond
(so the fish cannot escape underneath the nets as they are pulled).
Seines and gill nets also have floats attached to the top ropes to help
the net form an enclosure:  the entire pond is netted with one sweep
of the net.
Netting a Pond
Let out as much water as possible.   NEVER LET THE WATER OUT COMPLETELY.
As the fish have less and less water in which to live, they become
excited and use up more oxygen when there is less available.  Plan on
harvesting while the water is draining out so the fish are caught before
they are stressed.  Or, drain the pond almost completely, and then let
water slowly trickle through while netting the fish.

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USING A SEINE  Place the net at one end of the pond and slowly draw
the edges down the sides of the pond.   Bring the middle of the net
across the pond.
When near the other side, begin
pulling the edges up onto the bank
so that the net forms a u-shape in
the pond.  Pull up the bottom
rope of the net along the pond
bottom until it breaks the water
surface.  At this point the net
is a bag shape and will hold the
fish in (some seines already have
a bag woven into them).

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Pick the fish up one by one and transfer them to buckets or tubs of
clear water for later weighing and transport.

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OTHER HARVESTING METHODS  Fish also can be harvested by other
methods.  One method is to catch them with a hook and a line, but this
method is time-consuming.  In some parts of the world fish are harvested
by dynamiting or poisoning the water.   But these methods are dangerous
and should never be done in a pond or any other waterway:  dynamite
and poisons can kill people and other animals, in addition to fish.
easier and cheaper methods than these.
Marketing Harvested Fish
Once fish are harvested, they must be marketed.   Marketing includes the
transportation and sale of fish.   As the introduction to the manual
pointed out, one very important thing to consider before building a
pond is the availability of a market.   If a market is further away,
the farmer must have transportation to it over passable roads.  If the
market is very near, he may want to advertise the date of his harvest
by word-of-mouth so that the people will come directly to the pond to
buy the fish.  Also, he may want to make an agreement with a tradesman
at the market so that he is sure he has a buyer for his fish when they
are harvested.  If there is no market, or if the farmer is going to use
all the fish himself, then he probably will want to preserve some of the
fish (see fish preservation).
Containers for storing
live fish being taken
to market.

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Transporting fresh fish to market must be carefully done, so that the fish
are not damaged.  Usually, fish are handled in the same way they were
handled when put into the pond.   If it is not possible to get the fish to
market right away, they must be preserved -- either on ice for quick sale
in a nearby market; or salted, dried, smoked, or canned if going to a
distant market.  These methods are discussed in the next section.
Remember:  Fish spoil very quickly in warm temperatures.  Sell or preserve
the fish right after harvesting.
After Harvest
After the pond is harvested, it should be prepared for the next stocking
of fish:
    *   Plow the bottom of the pond
    *   Clear out predators, sticks, rocks, etc.
    *   Dry the pond bottom until the soil cracks
    *   Put lime on the pond bottom
    *   Wait two weeks
    *   Add water to the pond
    *   Check the water quality
    *   Put new fish into the pond
    *   Begin daily and monthly management of fish and ponds
    *   Breed
    *   Market
    *   Harvest
    *   Begin again

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                        MAKING A SEINE
A seine can be made using materials found in the market.  The materials
needed are:
          *   rope
          *   cork floats
           *  lead sinkers (or-something heavy to help the net sink)
          *   netting
          *   sewing needle for nets
The directions for making the net are as follows:
    *   Tie a rope that will be used for the top and bottom lines
       between two trees.  Use nylon rope, if possible, because it
       will last longer than cotton or hemp.
    *   Mark each rope at 15cm intervals.   Make sure the rope is
       longer than the final net by a few meters.
    *   Stretch the netting until the meshes close completely; then
       count the number of meshes in a 23cm section.  Good netting
       for a general seine will have 6 to 9 meshes in a 23cm stretched

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    *   Use nylon string that is very strong.   Wind a long section on
       a net needle.  Then tie the end onto the lead line rope (top
       rope) at the first marking.  Pass the needle through the number
       of meshes counted in the 23cm section of netting.  Tie the
       string on the rope at the second marking.
    *   Repeat the process until the last marking on the top rope is
    *   Pound the sinkers, or string them, onto the bottom rope at the
       15cm intervals.  Tie the cork floats onto the top rope at the
       same intervals.
    *   String the bottom line onto the netting in the same way as the
       top line.
REMEMBER:  The net must be washed, repaired, dried in the shade, folded,
           and put away in a cool, dry place after each use.  A net
           which is taken care of in this way will last much longer.
8           Preserving Fish
Fish that are not taken to the market fresh must be preserved in some way
after harvesting.  All fish have bacteria in their intestines; as soon as
they die, these bacteria begin to multiply, and the process of decay begins
So the first thing which must be done -- as soon as possible -- is to remove
the intestines.  After this is done, go on to preserve the fish in
the way chosen.
There are a number of ways to preserve fish:   salting and smoking are
discussed here in some detail.
Salting Fish
Salting is a very old method of preserving fish.   Salting depends on the
size of the fish, the species, and on the amount and quality of the
salt used.  Fish which have been salted well last a long time without
The most important factor in salting fish is the quality of the fish
being salted.  Use only fresh fish:  fish which have been lying around
for hours are not good for salting.   Also, use only clean equipment and
clean fish.
   *   Clean sharp knife
   *   Salt -- about 20kg for each 100kg of fish
   *   Containers for washing fish (buckets, tubs, drums)
   *   Flat working surface (table, flat stones)
   *   Containers for holding waste (parts of the fish not used)

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   *   Waterproof boxes or jars to hold salted fish (glass or wood;
      not metal unless the metal is stainless steel)
   *   Boards and weights (to press down the fish)
   *   Slats or lines for drying the fish
   *   Small shelter to cover fish while drying
There are four major steps:  gutting and cleaning; salting; washing and
drying to remove excess salt; and, finally, air drying.
Gut and Clean the Fish.

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   *   Gut the fish by cutting along the belly from the gills to
      the anal vent.
   *   Remove the guts and the black membrane in the gut cavity.
   *   Cut off the head now, if preferred; it is not necessary.
   *   Bleed the fish by removing the gills and all blood vessels
      after cutting open the throat.
   *   Cut the fish into the right shape for salting:  small fish
      may be left whole; larger fish should be split in half from
      head to tail, so that all the fish flesh will be exposed to
      the salt.

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Salt the Fish.
   *   Sprinkle a layer of salt on the bottom of the container
      which will hold the fish.
   *   Place a layer of fish, flesh side up, on the salt.  Do not
      let the fish lay on top of each other.
   *   Cover the fish with a thin layer of salt.
   *   Continue to place fish, then salt, almost to the top of
      the container.
   *   Place the last fish layer with the skin side up.  Sprinkle
      with salt; the last layer must be salt.
   *   Place boards and weights on top of the fish in the container
      to press them down.
   *   Leave the fish in the container for 15 days.  Add salt
      as necessary, until the fish are "struck through" -- thoroughly
      full of salt.  As the fish lie in the salt, the
      salt draws out all the moisture in their flesh.  This
      moisture forms a solution (brine) with the salt as the
      salt dissolves.  It is necessary to add more salt as the 
      salt is diluted in the solution.   As the moisture is removed
      from the fish by the salt, the level of fish in the container
   *   Add more fish, skin side up, and also more layers of salt as
      the level of fish falls.

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Wash and Dry the Fish.
   *   Remove the fish from the container when they are fully
      salted.   The fish are properly salted when they are firm
      and have a whitish salt layer on their flesh.
   *   Wash the fish in clear, clean, sea water or brine.
   *   Place the fish on a flat surface and press them down with
      boards and weights to make them as flat as possible before
Air Dry the Fish.
   *   Dry the fish in the sun and in the air, or use heating and
      fans.   Usually fish are dried outside in an area that is
      exposed to sun and wind and is very clean.
   *   Dry the fish under a shelter of leaves or branches for the
      first few days, so that they do not dry too quickly.

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   *   Put the fish into as much sunlight as possible, after the
      first few days.
   *   Lay the fish on triangular slats or hang the fish by their
      tails from fish lines strung up between trees.

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   *   Cover the fish if it rains.   Any moisture at all, at this
      stage in the salting process, will cause the fish to spoil.
   *   Dry the fish for about six days.
   *   Pack and store the fish in waterproof containers.
Soak salted fish in fresh water overnight.   Change the water at least once
during this time.  The soaking removes the salt; the longer the fish is
soaked, the more salt is removed.   After the fish has been soaked, it can
be used in any way that fresh fish is used.
Smoking Fish
Smoked fish does not last as long as salted fish, because it must be refrigerated,
frozen, or canned if it is to be stored.   Smoked fish are prepared
in a smoke house which is merely a shed or a box over a fire which
is controlled so that it produces smoke instead of flames.  The fish are
merely hung inside the smokehouse so that they are surrounded by smoke.
It takes about six hours to smoke fish so that they can be eaten or stored.
Smoked fish are prepared like fish for salting.   After they are bled, and
gutted, they are split from head to tail.   They are then washed in freshwater
and placed in a saltwater brine made by dissolving 1kg of salt in one liter
of water for one hour.  Then the fish are removed from the brine and washed
in clean, fresh, water again.   The fish are then drained and hung in a cool
breezy place for about an hour.

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At this point, the fire can be
built in the smokehouse.  When
it is smoking properly, place
the fish on hooks and hang
(or tie) the fish in the top
of the smokehouse.  Make sure
the fish are placed securely
so they will not fall.  Watch
the fire carefully to make
sure it is smoking, and not
burning, the fish.
After the fish are smoked for
six hours, they can be eaten
immediately, or stored in jars
(to be canned), or stored frozen
or refrigerated until they
are eaten.
Smoked fish do not last as long as salted fish, so do not smoke all of the
fish, unless it will be used soon after harvesting.
Other Preserving Methods
Fish can also be preserved by simple air drying, or by canning.  Air
drying involves only cleaning and washing the fish and drying them in
the sun and wind until they are a clear white color.   Canning is a much
more complicated process.  Canning must be done very carefully:  fish
can contain many bacteria which must be killed before canning.  If fish
are canned with this bacteria still in them, the fish will spoil.  People
who eat canned fish which is spoiled can become very sick.  A farmer who
wishes to can his fish should arrange with a canning factory to take part
of his harvest and can it for him.   A farmer should not try to can fish
at home unless he has expert help.
Often fish are preserved by freezing.   Freezing requires a constant
supply of electricity -- which most farmers do not have.  If electricity
is available, however, freezing is one of the easiest and safest ways
to preserve fish.  In this method, the fish are gutted, cleaned, cut
up (if desired), placed into containers, and put into freezers.  Frozen
fish can last for a very long time, if they are not thawed (unfrozen).
Once frozen fish are thawed, they must be used immediately, or they will
Spoiled Fish
Even spoiled fish can be used -- although it cannot be eaten by human
beings.  Spoiled fish can be cut up and boiled, then dried in the sun or
cooked in an oven until it is very flaky.   Once this is done, grind the
fish into a powder and mix it with powders of plants:   this makes a very
nutritious food for fish in ponds.   The powder can be used as a powder,
or it can be mixed with something to make it stick together so that the
powder can be pressed into pellets for fish.
Spoiled fish, and even the guts of fish that have been used in some other
way, are called "trash" fish.   The powder is called "fish meal."  Fish
meal is used to feed fingerlings or even brood stock.   Fish meal is one
of the best fish foods for pond fish.
9           Problems of Fish in Ponds
Fish cultured in ponds can have problems:   they can be stressed by a
lack of oxygen; they can be eaten by predators; they can be infested by
parasites.  These problems and some solutions to these problems are
discussed in this section.
Diseases of pond fish are caused by fungi, bacteria, protozoans, worms,
and crustaceans.  Usually diseases can be controlled by proper pond
management, which includes draining the pond, drying it, and liming it
periodically, and also by preventing wild fish or unfiltered water from
entering the pond.  Some diseases are fatal, but many can be controlled
by treating the pond or the fish with chemicals.
Some diseases attack fish in ponds because some other factor is causing
stress:  overcrowding, low oxygen levels, or not enough food.   All of
these conditions weaken the fish so they can get diseases more easily.
The farmer must watch his fish for signs of stress and disease.  Any
change in normal behavior may be a sign of disease; for example, gasping
at the surface for air, rubbing the body or head against the sides of
the pond, or ragged fins and sores on the body.   Something is wrong when
a fish population stops eating suddenly.   So the farmer must check the
fish often (see "Management"), especially in very hot weather.
FUNGAL DISEASES  These diseases are caused by fungi.
Gill Rot.  This is a disease caused by the filamentous fungus, Branchiomyces
sanguinis.  This disease is first noticed by a red spotting on the
gills.  Later, the gills become greyish-white and stop working.  When the
gills stop working, the fish suffocate and die.   Gill rot is most common
during the hot part of the year and is sometimes associated with large
amounts of dung and a "bloom" of plankton.
      Treatment:   Remove dead fish from the pond; the remaining fish
                  will probably recover.  Drain the pond and dry the
                  bottom.  Treat the pond with quicklime or copper
                  sulphate to kill the fungus spores.  Fill the pond
                  again.  Add quicklime every few weeks until there
                  is no more sign of the disease.

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Saprolegnia.  This fungus is often associated with Gill Rot.  It attacks
weakened places (e.g., bruises from handling) on fish.   Since it hits
already weakened fish, Saprolegnia attacks fish already trying to fight
other diseases.  Saprolegnia looks like fuzzy, white cotton wool and is
often in tufts on the body of the fish.   Saprolegnia by itself can kill
eggs and fry, but does not kill adult fish.   Indian carp are very susceptible
to this disease, and common carp eggs are attacked frequently.
      Treatment:   Use the same treatment as outlined for Gill Rot.
BACTERIAL DISEASES  These are caused by parasites which are
actually bacteria.
Furunculosis.  This is the most important bacterial disease.  This disease
causes-ulcers or abcesses in muscle tissue.   It then breaks through
the skin, and, eventually, becomes a site for fungus infections, like
Saprolegnia.  This disease attacks in the spring, and is most often found
in more temperate species, like trout.
      Treatment:   Drain the pond and treat it with slaked lime.
                  Disinfect every tool used in the pond (nets,
                  feeding rings, etc.).
Infectious Dropsy.  This is caused by the bacterium, Pseudomonas punctata.
The symptoms are a swelling of the fishes' belly with water, ulcers on
the skin, lengthening of the fins, and deformation of the backbone.
      Treatment:   Prevent diseased fish from entering the pond.
                  Bury and burn the dead fish.
Columnaris.  This is another bacterial disease which causes discolored
patches on the body, loss of scales, and, often, death.   This disease
can look like a fungal disease, but it is not.   If possible, it should
be examined under the microscope for positive identification.  It is
caused by the bacteria Chondrococcus columnaris and Cytophaga columnaris
and is often associated with low oxygen levels.
      Treatment:   Give fish a feed which has terramycin in it.  If
                  it is very bad, place each infected fish in a dip
                  (bath) of copper sulfate (2 minutes in a solution
                  of 1 to 2,000) or a dip of malachite green (10 to
                  30 seconds in a solution of I to 15,000).  Treat
                  the pond with 1 ppm of copper sulfate.

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Ichthyophthirius multifilis.   This is the worst protozoan disease.   The
"ich" disease is caused by a ciliate which forms white spots or pimples
on the skin and fins of the fish.   Each parasite produces thousands of
spores, which can then infect other fish in the pond.
      Treatment:   Drain the pond, and lime it.   Or treat the fish
                  with chemicals as follows:
                  Formalin            200-250ppm   daily bath
                                           15ppm    in pond
                  Malachite green         1.25ppm    daily bath/30 minutes
                                          0.5ppm    in pond
                  Methylene blue            2ppm   daily bath
                  Acriflavin               10ppm    3-20 daily baths
                  Salt                  7,000ppm   several daily baths
Costia and Trichodina.  These are two other ciliate diseases.  They are
cause by microscopic organisms which attack the skin of fish and cause
lesions.  Tilapia, the very resistant fish, are attacked by the Trichodina

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These ciliates cannot be seen by the naked eye, but the lesions and sores
that they cause can be seen by looking closely at the fish.
      Treatment:  Add 3ppm of potassium permanganate to pond.  Or dip
                  the fish in baths of 5 to 10% sodium chloride (salt)
                  for 5 to 20 minutes daily for up to one week.
Lernea.  The anchor worm is the most common disease of this type (a copepod).
This worm attacks the gills or any other part of the body.  It burrows into
the fish, leaving its two egg cases protruding on the outside of the fish.
Lernea causes red sores, and makes the fish thin so that their market
value is much lower.

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      Treatment:   Add castor oil in a thin film over the surface of
                  the pond.  Treat fish infected with young Lernea
                  in a formalin bath, or remove each parasite by hand.

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Arqulus.  Argulus is the fish louse.  It is a flat, pinkish-red disc
that clings to the skin, fins, mouth, or gills.   It sucks blood with
a piercing organ, which also injects poisons.   Young fish may die.
      Treatment:   Drain and lime the pond.   Or place the fish
                  in a bath of 3 to 5% salt, or 250ppm of formalin
                  for 1 hour.
WORM PARASITES  Most of these are external parasites.
Dactylogyrus.  This parasite attacks the gills of young fish.  The fish
are exposed to this worm when they are between 2 and 5cm long.
      Treatment:   Manage the pond well so that fingerlings
                  grow rapidly past the stage when they are
                  susceptible to Dactylogyrus.
Gyrodactylus.  This parasite burrows into the blood vessels of fish
through the skin, causing the fish to appear reddish with sores.  This
worm can cause fish to die from emaciation.
      Treatment:   Treat ponds with 5 ppm formalin.   Treat fish
                  individually in a bath of 25ppm formalin.
Bothriocephalus gowkongensis.   This is the tapeworm which often attacks
the Chinese carp, especially grass carp.   It is difficult to treat this
worm; it is found in the fishes intestines.

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General Treatments
Farmers often will have trouble finding the proper chemicals for treating
their ponds or deciding which disease the fish have and which treatment
to give.  Here are some general treatments:  any of these treatments will
help an infected pond.
      Baths:   Potassium permanganate        4ppm
              Salt                       3-5%
              Copper sulfate             500ppm for 1-2 minutes
              Formalin                   250ppm for 1 hour
              Malachite green             67ppm for 10-30 seconds
Or the farmer can use unslaked lime directly in the pond.
Some pond owners always treat new brood stock with a one-hour bath in
10ppm of potassium permanganate, and then transfer the fish to a bath of
15ppm of formalin for 4 to 12 hours.   This ensures that no parasites will
be introduced into the pond with the brood stock.
Other Problems
Other problems are caused by deficiency or environmental factors.
Deficiency problems appear because the fish are missing some factor they
need to grow and be healthy.   The missing factor can be a lack of essential
elements like vitamins or minerals.   This lack is difficult to detect
until a problem exists.  So the only way to prevent this kind of deficiency
is to be sure the fish are eating the right kinds of food.
Environmental problems are caused by some change in the pond environment
which places a stress on the fish, such as a rapid change in water
temperature or an increase in pond water acidity.   These are not diseases
but problems of fish in ponds which can be controlled by watching the
water and soil quality of the fish pond, and by preventing any rapid
changes from occurring.

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Other problems occur in fish ponds when other animals eat the fish.
Frogs, snakes, and birds eat young fish and must be kept out of ponds.
The worst predators, of course, are carnivorous fishes, like the
Clarias catfishes.  Prevent these fish from entering the ponds by
screening the water inlet.
In any pond, all unwanted (trash) fish and predators must be removed
before stocking the pond.  If the pond can be emptied, simply drain the
pond, plow and dry the bottom, etc.   If the pond cannot be drained, seine
the pond as completely as possible.   However, many fish escape the net by
staying at the edges of the pond.   The best way to get rid of the
predators is to poison the pond water in a pond which cannot be drained.
USING POISON  The most common poison for use in fish ponds is rotenone.
Rotenone can be purchased -- as a liquid or powder -- or it can be gotten
from the roots of the derris plant.   To make rotenone, collect derris
roots and pound them until a milky-white fluid can be squeezed out.  This
fluid contains rotenone.  Apply one kilogram of derris root for every
hectare of pond surface area.   If using powdered rotenone, use only 0.05
kg/ha.  The powder should be dissolved in water and dipped into the pond
from buckets.
Other poisons used in fish ponds are quicklime, teaseed cake, camelia
seed cake, tobacco waste, and powdered croton seed.   These are some
application rates:
            Quicklime :           160 kg/ha
            Teaseed Cake :        150 kg/ha
            Camelia Seed Cake :   50 to 200 kg/ha, depending on depth
            Powdered Croton
             Seed :               50 to 200 kg/ha, depending on depth
            Tobacco Waste :       150 to 200 kg/ha
Most of these natural poisons will degrade (break down) and disappear
from the water in 7 to 12 days.   After this period, seine the pond
again.  If no live fish are caught, stock the pond.
There are many chemicals which can be used to poison predators in fish
ponds.  However, many of them stay in the ground too long.  Others are
dangerous.  One of the chemicals which can be used safely is saponin,
which is a component of teaseed cake.   Apply a dose of 0.5 ppm in the
In most places, there are fishermen and farmers who know of some local
plant which causes fish to die.   For example, in India large ponds
that cannot be drained are poisoned with Mahuca oil cake (Mahuca
latifolia, syn. Bassia latifolia), applied at a rate of 150 to 250 ppm
(1500 to 2500 kg/ha per meter of water depth).   This plant poison
breaks down in 10 to 20 days.   These types of poison are all better
sources of poison than are chemicals.   Many times, when there is a
tree that overhangs a pond, fish will be killed when the tree leaves
drop into the pond.  Watch for plants which do this, and use them in ponds
instead of poisons in a chemical form.
                       SUMMARY:    FISH DISEASES & TREATMENTS
DISEASE                  DISEASE ORGANISM               IN PONDS                       IN BATHS
Gill Rot              Branchiomyces sanguinis       Quicklime
                                                    Copper Sulfate
Saprolegnia           Saprolegnia                   Quicklime
                                                    Copper Sulfate
Furunculosis                                         Slaked lime in
                                                      Drained Pond
Infectious Dropsy     Pseudomonas punctata          Burn or Bury Dead Fish
Columnaris            Chondrococcus columnaris       Copper Sulfate 1ppm          Copper Sulfate 500ppm
                      Cytophaga columnaris                                         for 2 minutes
                                                                                Malachite Green 67ppm
                                                                                  for 10-30 seconds
Ich                   Ichthyophthirius multifilis   Formalin 15ppm              Formalin 200-250ppm
                                                    Malachite Green 0.5ppm       Malachite Green 1.25ppm     
                                                                                Methylene Blue 2ppm
                                                                                Salt 7000ppm
                                                                                Acriflavin 10ppm
Costiasis and         Costia and Trichodina         Potassium Permanganate      Salt 5-10% for 5-10
  Trichodiniasis                                       3ppm                         minutes daily   
Anchor Worm           Lernea                        Castor Oil                  Formalin
Fish Louse            Argulus                                                    Salt 3-5%
                                                                                Formalin 250ppm for 1 hour
Nematodes             Dactylogyrus and Gyrodactylus Formalin 5ppm                Formalin 25ppm
10           Other Methods of Fish Culture
Fish culture in ponds is the primary method of freshwater fish culture.
However, there are other methods of fish culture used in places where
ponds are not possible.
Fish Culture in Dams and Reservoirs
Water contained by dams and reservoirs is sometimes used for fish culture.
These waters can be stocked with fry or fingerlings; the adults are later
harvested with nets.  Raising fish in these waters is more difficult
than in ponds because these waters cannot be drained, and the predators
cannot be removed.  Also, it is not possible to feed, fertilize, or
poison the water, so natural nutrients must provide enough fish food.
But if there is no other water source available, culture in dams and
reservoirs can work.
Culturing fish in
waters held by dams
and reservoirs can
be done more easily
if the fish are placed
in fish cages and
pens.  These structures
confine the fish to a
certain place and give
more control over the

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In Cages
In many parts of the world, the only water available is flowing water
or large bodies of water where it is not possible to divert the water
into a pond.  In these waters, it is possible to grow fish in small
cages.  Cage culture can also be practiced in areas like swamps where
there is water not being used for any other purpose.
Cages can be rectangular boxes, bamboo cylinders, or anything that
can be floated in a water current so that the water passes through.

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In addition to bamboo, cages can be made out of such materials as wire
screen, nylon mesh, and wood.   All cages must be anchored so that they
do not float away.
Cage culture is used in some countries in very fertile waters (polluted
from sewage) with very good results.   Fish in cages usually get their
food from the water as it floats past the stationary cage, but in some
cases, the caged fish are fed pellets of food daily.

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Fast flowing water is best for cage culture.   If the water is not flowing
very fast, problems such as oxygen lack and competition for food can
occur.  These can be big problems in cages because there are usually more
fish placed in the small area of the cage than would normally be in the
same area in the pond.
Cage culture is still experimental, but in ideal conditions, good growth
rates have been shown by fish that were grown in cages and given extra food.

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Cages also are used inside ponds
for holding fish between harvest
and the time they are sold.
And, sometimes, cages are used
as breeding tanks -- like hapas.
Cages are also used to carry
fish caught in rivers to market,
strapped alongside a boat.
In Pens
Fish can also be cultured in pens inside lakes or offshore areas.  Fish
culture in pens has been done in Israel and Scotland for years, and is
now being done in some Asian countries.   Pens are constructed of bamboo
or wooden poles that are forced down into the lake or shore bottom.
Then nets are strung from pole to pole to form an enclosure.  The nets
are anchored into the lake bottom with weights or sinkers, and the fish
are placed inside the pen for culture.   Fish grown in pens can be
controlled a little better than fish in cages because pens are larger
(fish pens can be comparable in size to regular fish ponds) and provide
more area and more food.

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Fish pens placed in fertile (productive) lakes have very good growth
rates.  In a fish pen placed in a major lake in the Philippines, silver
carp stocked at 7 grams gained an average of 4 grams a day in a 52-day
growing season.
Fish pens have many good points:   they require no extra feeding of fish,
no fertilization, and very little maintenance (although a lot of care
is given to the nets).  The fish are stocked and harvested later at the
end of their growing season.   Fish pens can work in areas where the
water is not very productive, but in these areas, the fish must be fed
supplementary foods.  Feeding rings are used so the food will stay in
the pen and not float out into the water.   Fish in pens are usually
harvested by gill nets; seines also may be used.

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There are some disadvantages to pens:
    *   Pens are expensive to build.   The netting used must be nylon
       or plastic so it does not rot, and poles must be treated
       so they do not become waterlogged and rot.  In the Philippines,
       it costs about $1,428 (U.S.) to build a one hectare pen, using
       nylon netting and bamboo poles.  This is comparable to the
       cost of a one-hectare fish pond, but a pen can be destroyed
       by a big storm and a pond will no+ be destroyed.
    *   A fish pen only lasts three to five years in the water.
    *   Fish pens are usually built in the shallow areas of a
       lake, where they use space many fish need to feed and
       spawn.   The pens, therefore, reduce the natural production
       in some lakes.
    *   Fishermen must go further out into the water to fish when
       pens are in the shallow areas.
Fish pens can also be built like fish cages so that they float.  Floating
fish pens are used most for marine fish research studies; they also can
be used in lakes.  Floating fish pens can be as small as one hectare
in size, or as large as 10 hectares.   They are not destroyed by storms
as easily as pens anchored to the bottom, and they can-be moved from
one site to another.
Fish pens may have an increasingly important role in future fish culture
activities around the world.
In Rice Paddies
This manual has already mentioned the practice of culturing fish in
fields with rice.  Here is further, brief mention of that subject.

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The farmer digs deep trenches all along the dikes of the paddy.  He then
floods the field and plants the rice.   After the rice has grown to
a height of 5cm or so, fish can be placed into the paddy field.
This culture method can be used only with fish that are resistant to
low oxygen levels and are not herbivores - herbivores might eat the young
rice plants.  Clarias catfishes are good fish to culture in rice
paddies because they ave accessory breathing organs which help them to
breathe even when the paddy gets dry and the water in the trenches gets
very low.
After the rice is harvested, the fish are caught in hand nets and sold.
This is not really a culture of fish, but a culture of rice with some
fish added.  It can be an easy way for a farmer who has no extra land on
which to build fish ponds to increase the total production of his land.
acclimate - to become adjusted to a change from the normal environment
(also acclimatize).
acid - a substance that can dissolve in water and is sour or bitter
in taste, and turns litmus paper from blue to red.
adhesive - a sticky substance; sticking or sticky to something else.
aeration - adding oxygen to water by spraying or bubbling air through
the water.
algae - small or large water plants from five classes of plants.
alkalinity - the ability to combine with an acid to form a salt.
aquaculture - the cultivation of animal and vegetable life in water.
area - the length times the width of a piece of land or other surface.
back washing - forcing water in the opposite direction from its
normal flow.
barbels - sensitive organs that hang down on the sides of the mouth
of certain fishes.
basic - having base forming elements (alkaline on reaction).
bloom - a very good growth of algae in a pond that has a strong green
bottom feeders - fish that feed on bottom organisms (organisms that
live in mud on the pond bottom).
breeding - the cycle of reproduction in animals.
brine - water that is saturated with common salt, or the water from
a salt water body (the ocean).
brood ponds - ponds where the fish used for breeding are kept.
brood stock - the fish used for breeding in fish ponds.
cage - an enclosure to hold fish in the water.
captivity - the state of being held in a confined place (fish in
ponds are captive).
carnivore - an organism that eats animal products.
centrifuge - the machine that uses centrifugal force to separate
materials of different densities.
compete - to fight for something against someone or thing.
contaminant - something that makes something else impure; a pollutant.
cooperative - an organization of people that are working together for
a common purpose.
dam - the wall of a fish pond.
debris - rubbish, garbage, anything that is not supposed to be in a
certain area (pond).
density - the number of fish in a pond.
dike - the wall of a fish pond.
diversion channel - a ditch that takes water from a stream or river
to a fish pond.
elevation - the height of land.
exotic species - fish cultured in ponds that are not native to the area.
fertility - being very productive.
fertilizer - anything added to water or soil to make it more productive.
fingerling - a fish that is about as long as a man's finger (6-10cm).
fishculture - the breeding and cultivation of fish in ponds.
fry - fish that have just hatched until they reach fingerling size.
genitals - reproductive organs.
genital opening - the opening on the fishes' body where the eggs or
sperm are released.
gills - the part of a fish that allows it to breathe in the water.
gravity - the tendency of things to fall downwards towards the center
of the earth.
hapa - the mesh enclosure in ponds where fish can be spawned.
herbivore - an organism that eats only plants and plant products.
hypophysation - hormone injection to induce breeding of fish.
hypophysis - the pituitary gland.
hormones - components that are secreted by glands of the body to cause
certain changes in the body's functions.
impermeable - a substance that nothing can leak thru.
induced spawning - causing a fish to spawn by injecting it with hormones.
introduced species - fish not native to an area that are used in fish
ponds of the area.
kakaban - an egg collector.
mortality rate - the rate of death.
natural food - food that a fish eats in nature.
niche - what an organism does; its job in the community.
nutrient - an ingredient of food that is healthful.
omnivore - an organism (like man) that can eat both plants and animals.
operculum - the gill covering.
oxygen - a gas that is necessary for all life.
pens - enclosures for fish culture on large bodies of water.
phytoplankton - tiny green or brown plants that are microscopic,
free-floating in water, that are used as food by fish.
photosynthesis - the process on which green plants produce food for
themselves and release oxygen into the water.
pituitary gland - the gland that releases hormones controlling the
reproductive cycle in animals (like fish).
plankton - the tiny plants and animals that grow in ponds that are
eaten by fish.
ponds - any enclosure that holds water so that fish can be grown
inside it.
predators - animals that prey on other animals.
productivity - ability to grow food in a pond, whether it is plankton
or fish.
reproduction - producing offspring.
respiration - breathing.
serrations - rough edges, like on a fishes' fin.
slope - the slant of land.
spawning - the release and fertilization of eggs and sperm.
stress - any change that is not normal in the environment that creates
trash fish - fish not wanted in the pond, or fish that are too small to
eat or spoiled fish.
watertight - impermeable.
zooplankton - small animals in ponds that can be seen with the naked eye.
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     for examination of water and wastewater.  13th ed. Am. Pub.
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     studies with the hybrid tilapia Tilapia nilotica X Tilapia
     mossambica.   FAO World Symposium on Warm Water Pond Fish
     Culture.   Rome, Italy.
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     Evaluation of eight species of fish for aquatic weed control.
     FAO World Symposium on Warm Water Pond Fish Culture.  Rome, Italy.
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     policy in low-income countries.  Charles Knight and Company,
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     experimental studies.  Zoology-Entomology Dept.   Series, Fisheries
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     Alabama.   28 p.
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10.  Bharadwaj, R. S., Stephen Crawford, and Lauren C. Watson.  1973
     Manual for fish culture in Rajasthan and Madhya Pradesh.
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11.  Boyd, Claude E. 1971.  Phosphorus dynamics in ponds.  Proceedings
     25th Ann. Conf. Southeastern Assoc. Game and Fish Commissioners:
12.  Boyd, Claude E., E. E. Prather, and Ronald W. Parks.  1975.
     Sudden morality of a massive phytoplankton bloom.  Weed
     Science.   23 (1):  61-67.
13.  Clemens, Howard P. and Kermit E. Sneed.  1962.   Bioassay and use
     of pituitary materials to spawn warm-water fishes.  Research
     Report 61, Bureau of Sport Fisheries and Wildlife, United States
     Department of Agriculture (USDA).  30 p.
14.  Crane, John S., et al.  1966.   Togo fish project manual.  United
     States Peace Corps.  Oklahoma University, Norman, Olkahoma.
     158 p.
15.  Delmendo, Medina N. and Robert H. Gedney.  1974.   Fish
     farming in pens - a new fishery business in Laguna de Bay.
     Laguna Lake Development Authority, Technical Paper 2.
     Pasig, Rizal, Philippines.
16.  Denyoh, F.M.K. 1966.  Pond fish culture development in Ghana.
     FAO World Symposium on Warm Water Pond Fish Culture.  Rome, Italy.
17.  Dillon, Olan W., Jr., et al.  Warm water fish ponds.   Farmer's
     Bulletin 2250.   USDA.  Washington, D.C. 14 p.
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     culture.   Part III. State Dept.   of Fish and Game, Kansas.
     Kansas State Printing office, Topeka, Kansas. 130 p.
19.  Eipper, A.W. and H.A. Gegier.  1965.   Fish management in New
     York farm ponds.  Cornell Extension Bull. 1089.  New York
     State College of Agriculture, Ithaca, New York.  39 p.
20.  Fidler, Gary.  1973.   Knowledge about your fish pond.  Bureau
     of Fisheries and the United States Peace Corps, Manila,
     Philippines.  28 p.
21.  Fijan, Nikola.  1966. Problems in carp fish pond fertilization.
     FAO World Symposium on Warm Water Pond Fish Culture.  Rome, Italy.
22.  Francis, Francis.  1865.   Fish culture:   a practical guide to the
     modern system of breeding and rearing fish.  Routledge,  Warne,
     and Routledge.  London.   320 p.
23.  Fridthjof, John.  1962.   Encouraging the use of protein-rich foods.
     FAO, Rome, Italy.  103 p.
24.  Gaines, John L., Jr., and Wilmer A. Rogers.  1975.   Some skin
     lesions of fishes.  The Pathology of Fishes.   University of
     Wisconsin Press.  Madison, Wisconsin:   429-441.
25.  Gracia, Demetrio M. and Pio D. Bersamin.  What you should know
     about carp culture.   Philippine Fisheries Commission, Intramuros,
     Manila, Philippines.  7 p.
26.  Gray, D. Leroy.  1970.   The biology of channel catfish production.
     Agricultural Extension Service, Circular 535.  University of
     Arkansas.   16 p.
27.  Grizzell, Roy A., Jr., Olan W. Dillon, Jr., and Edward G.
     Sullivan.   1969.  Catfish farming - a new farm crop.  Farmer's
     Bulletin 2244.  USDA.   22 p.
28.  Hara, Shiro.  1972.   Experiment on induced spawning of catfish
     (hito) stripping method and observations on the feeding of
     fry.   P.F.C. Freshwater Fisheries Investigation Unit, Los
     Banos, Laguna, Philippines. 11 p.
29.  Hickling, C.F. 1961.  Tropical inland fisheries.   Longmans, Ltd.
     London.   287 p.
30.  Hickling, C.F. 1968.   The farming of fish.   Pergamon Press, Ltd.
     London.   88 p.
31.  Hickling, C.F. 1971.  Fish culture.   2nd. ed. Faber and Faber,
     London.   317 p.
32.  Hora, S.L. and T.V.R. Pillay.  1962.   Handbook on Fish culture in
     the Indo-Pacific region.  FAO Fisheries Biology Technical
     Report 14. Rome, Italy.  204 p.   (xeroxed copy)
33.  Huet, Marcel, in collaboration with J.A. Timmermans.  1970.
     Textbook of fish culture.  Fishery News (Books) Ltd., London.
     436 p. (translated from French by Henry Kahn)
34.  Hutchinson, G. Evelyn.  1957.   A treatise on limnology.  John
     Wiley & Sons, Inc., New York.  1015 p.
35.  Jeffrey, Norris B. 1969.  Some aspects of the ecology of fish ponds.
     Proceedings 1969 Fish Farming Conf., Texas Agric.  Extension
     Service, Dept. Wildl. Science, College of Agriculture.  Texas
     A & M University:  40-42.
36.  Lagler, Karl F., John E.  Bardach, and Robert R.   Miller.  1962.
     Ichthyology.  John Wiley & Sons, Inc., New York.  545 P.
37.  Lawrence, J.M. 1949.  Construction of farm fish ponds.  Circular
     92.   Agric. Exp. Station, Auburn, Alabama. 55 p.
38.  Lichtkoppler, Frank.  Basic village pond fish production. U.S.
     Peace Corps, Madhya Pradesh, India. 11 p.
39.  Maar, A., M.A.E. Mortimer, and I. Van der Lingen.  1966.  Fish
     culture in central east Africa.  FAO, Rome, Italy.   158 p.
40.  Manual on Fishermen's Cooperatives.  FAO Fisheries Studies 13.
     FAO, Rome, Italy. 124 p.
41.  McLarney, William O. (ed.).  1973.   The backyard fish farm
     workbook for 1973.  Organic Gardening and Farming.  Rodale Press
     Inc. The New Alchemy Institute, Woods Hole, Mass.
42.  McLarney, William O. and J.R. Hunter.  1975.   A new low-cost
     method of sealing pond bottoms.  The Journal of the New
     Alchemists.   3:  85.
43.  Meschkat, A. 1966.  The status of warm-water fish culture in Africa.
     FAO World Symposium on Warm Water Pond Fish Culture.  Rome, Italy.
44.  Meyer, Fred P. Treatment tips - how to determine quantities for
     chemical treatments in fish farming.  Bureau of Sport Fisheries
     and Wildlife.  Fish Farming Exper.   Sta., Stuttgart, Arkansas.
     US Dept. of the Interior.  20 p.
45.  Meyer, Fred P., K.E. Sneed, and P.T. Eschmeyer. (eds.).  1973.
     Second report to the fish farmers.  Resource Pub. 113. Bu. Sport
     Fish. and Wildl., USDI.  123 p.
46.  Odum, Eugene P. 1971.  Fundamentals of Ecology.   3rd ed. W.B.
     Saunders Co., and Toppan Co., Ltd., Tokyo, Japan. 574 P.
47.  Ong, Kee Bian.  1968.   Fish culture.  Rorneo Literature Bureau.
     Asiatic Lithographic Printing Press, Ltd. Hong Kong. 80 p.
48.  Patino R., Anibal.  Cultivo experimental de peces en estanques.
     Cespedesia II (5):  75-127.   (translated by Wm. O. McLarney in
     the Journal of the New Alchemists. 3:86-90)
49.  Prowse, G.A. 1968.  Some basic concepts on fish culture.  FAO
     Indo-Pacific Research Council, 13th Session.  Brisbane,
     Queensland, Australia.
50.  Rawson, G.C. 1966.  A short guide to fish preservation.  FAO,
     Rome, Italy. 67 p.
51.  Report to the fish farmers.  1970.   Resource Pub. 83. Bu. of
     Sport Fish. and Wildl., USDI.  124 p.
52.  Rogers, Wilmer A. and John L. Gaines. 1975.  Lesion Of Protozoan
     diseases in fish.  The Pathology of Fishes.   University of
     Wisconsin Press, Madison, Wisconsin:  117-141.
53.  Samaka-Service Center.  1962.   The Samaka guide to homesite farming.
     Samaka Service Center, Manila Philippines.  166 p.
54.  Shell, E.W. 1966.   Monosex culture of male Tilapia nilotica
     (Linn.) in ponds stocked at 3 rates.  FAO World Symposium on
     Warm Water Ponf Fish Culture.  Rome, Italy.
55.  Shook, Marilyn.  1974.   Research Status Report:   Experimental fish
     pen project.  Bureau of Fisheries, Manila, Philippines. 7 p.
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     of catfish (Clarias spp.) in Thailand.  Fisheries Dept.,
     Bangkok, Thailand.
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     suitability for fish culture.  9th Pacific Science Congr.,
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     pond fishes in Alabama.  Transac. Am. Fish. Soc. 89(2):  142-148.
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     in Ponds.   FAO World Symposium on Warm Water Pond Fish Culture.
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     and their prevention.  FAO World Symposium on Warm Water Pond
     Fish Culture.  Rome, Italy.
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     poisoning of overcrowded fish Populations.  Circ. 113. Agric.
     Exp. Sta., Auburn, Alabama.  15 p.
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     fertilization of ponds.  Proceedings 17th Ann. Conf., Southeastern
     Assoc.   Game and Fish Commissioners, Arkansas:   213-217.
63.  Taverner, John.  1600.   Certaine experiments concerning fish and
     fruite.   London. 38 P. (reprinted 1968.   Da Capo Press and
     Theatrum Orbis Terrarum Ltd., Amsterdam and New York).
64.  Torrans, Eugene Leslie.  1973.   Fish culture in Cameroon.  Peace
     Corps Program and Training Journal.  ACTION, Washington, D.C.
     1(5):   14-47.
65.  University of Rhode Island Marine Memorandum 30.  1972.  Fisheries
     cooperatives:  Their formation and operation.  Marine Advisory
     Service.   University of Rhode island, Narragansett, Rhode
     Island. 18 p.
66.  World Neighbors in Action.  Raising fish in local farm ponds means
     protein and profit in Paraguay.  World Neighbors International
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     Handbook.   VITA, Mt. Rainier, Maryland. 387 p.
68.  Yashouv, A.   Interaction between the common carp (Cyprinus
     carpio) and the silver carp (Hypophthalmichthys molitrix)
     in fish ponds.  Fish Culture Research Station, Dor, Israel.
1 gram (gm)               =     1000 milligrams (mg)
1 kilogram (kg)           =     1000 gm = 2.2 pounds (lb)
1 mg/l                    =     1 part per million (ppm)
1 liter (l)               =     1000 milliliters (ml) = 0.26 gallons (gals)
1 inch (in)               =     2.54 centimeters (cm)
1 foot (ft)               =     30.5 cm
1 meter (m)               =     100 cm = 1000 millimeters (mm) = 39,37 inches
1 are                     =     100 square meters ([m.sup.2])
1 hectare (ha)            =     10,000 [m.sup.2] = 100 ares = 2.5 acres
[degrees] Centigrade (C)  =     5/9 x ([degrees] F - 32)
[degrees] Fahrenheit (F)  =     (9/5 x [degrees] C) + 32
Acclimate - p. 49
Acids - p. 15, 17, 90
Alkalinity - p. 89 - 90
Anal fin - p. 34
Anal vent - p. 34
Anchor worm - p. 168 - 169
Anguilla japonica - p. 39, 50
Anus - p. 35
Application rates - p. 97 - 100
Argulus - p. 169
Aristichthys nobilis - p. 39, 43
Aquaculture - p. 1
Bacterial diseases - p. 166
Barbels - p. 35
Barbus gonionotus - p. 39, 47
Barrage ponds - p. 19 - 21
Black carp - p. 40, 44
Bighead carp - p. 2, 29, 39, 43
Blooms - p. 93
Bothriocephalus gowkongensis - p. 170
Bottom-water overflow - p. 62 - 63
Breeding - p. 19 (see "Spawning")
Brood stock - p. 128 - 130
Buffering ability - p. 90
Cage culture - p. 176 - 177
Calcium - p. 90
Carassius auratus - p. 39, 50
Carassius carassius - p. 39, 50
Carbohydrates - p. 3 - 4
Carbon dioxide - p. 83 - 87
Carp - p. 2
  Chinese - p. 2, 43 - 45, 109, 119, 135, 146 - 147
  Common - p. 2, 37, 40 - 42, 108 - 109, 118, 130 - 132, 148
  Indian - p. 45 - 46, 109, 119, 136, 148
Carpenter's level - p. 56
Catch basin - p. 39, 45
Catla - p. 39, 45
Catla catla - p. 39, 45
Caudal fin - p. 33
Caudal peduncle - p. 33
Centrifuge - p. 143 - 145
Chanos chanos - p. 39, 49
Characteristics of fish - p. 33
Cirrhina molitorella - p. 39, 44
Cirrhina mrigala - p. 39, 46
Clarias batrachus - p. 39, 47, 138
Clarias catfish - p. 29, 39, 47, 138, 147
Clarias macrocephalus - p. 39, 47, 138, 147
Clay soil - p. 15 - 16
Columnaris - p. 167
Compost - p. 96 - 97
Construction - p. 53 - 78
Cooperatives - p. 8
Costia - p. 168
Crucian carp - p. 39, 50
Crustacean parasites - p. 168
Ctenopharyngodon idellus - p. 39, 44
Culture in pens - p. 177
Cyprinus carpio - p. 40 (see "common carp")
Dactylogyrus - p. 169
Dams - p. 19, 54
Depth of ponds - p. 25
Dikes - p. 54
Diseases - p. 165
Diversion ponds - p. 21 - 23
Dorsal fin - p. 33
Double-sleeve overflow - p. 63
Drainage ditches - p. 20, 69
Drainage systems - p. 55, 60 - 69
Eggs - p. 36
Eels - p. 39, 50, 140
Elbow joint - p. 62
Elements - p. 4
Exotic species - p. 38
Fats - p. 3 - 4
Feeding - p. 116 - 117
Feeding ring - p. 117
Fertility - p. 16 - 17
Fertilizers - p. 93, 120
  Inorganic - p. 99 - 100
  Organic - p. 95 - 96
Filters - p. 14, 70 - 73, 116
Fingerlings - p. 19, 37, 113, 123 - 128
Fish culture - p. 1
Fish louse - p. 169
Fish farming - p. 6
Fish meal - p. 163
Food - p. 7, 100 - 106
   Natural - p. 101
   Supplementary - p. 101, 117 - 119
Food quotient - p. 101 - 102
Fry - p. 19, 36, 110 - 113, 123 - 128
Fungal diseases - p. 165
Furunculosis - p. 166
Genital opening - p. 34
Genital papilla - p. 35
Gill net - p. 149
Gill rakers - p. 34
Gills - p. 34
Gley - p. 77
Goldfish - p. 39, 50
Gourami - p. 40, 46, 47, 137
   Kissing - p. 40, 49, 138
   Snakeskin - p. 40, 49, 138
   Three-spot - p. 40, 49, 138
Gravity - p. 17
Gyrodactylus - p. 169
Hapa - p. 136 - 137
Hard water - p. 90
Hardness - p. 89 - 90
Harvesting - p. 149 - 156
Helostoma temmincki - p. 40, 49
Heterotis niloticus - p. 40, 48, 139
Hormone injection - p. 141
Hybrid vigor - p. 38
Hydrilla  verticillata - p. 49, 84, 138
Hypophysis - P. 142
Hypothalmichthys molitrix - p. 40, 43
Ichthyophthirius multifilis - p. 167 - 168
Inlet, water - p. 20 - 21, 55, 69 - 70
Inorganic fertilizers - p. 99 - 100
Induced spawning - p. 141 - 148
Kakaban - p. 132
Key - p. 75 - 76
Kissing gourami - p. 40, 49, 138
Labeo rohita - p.  40 -45
Lateral line - p.  34
Lernea - p. 168 - 169
Levee - p. 54
Level - p. 56
Lime - p. 79 - 80
Limestone - p. 80
Litmus paper - p. 89
Magnesium - p. 90
Management - p. 107 - 148
   Daily - p. 115
   Monthly - p. 121
Marketing - P. 152 - 153
Milkfish - p. 39, 49, 50, 140
Monk - p. 65 - 69
Monoculture - p. 26 - 28
Monosex culture - p. 30 - 31
Mortality rate - p. 125
Mrigal - p. 39, 46
Mud carp - p. 40, 44
Mugil cephalus - p. 40, 51
Mullet - p. 40, 51, 140
Mylopharyngodon piceus - p. 40, 44
Nets - p. 149
Nutrients - p. 3, 16 - 17, 92 - 93
Number of ponds - p. 23
Operculum - p. 34
Organic fertilizers - p. 95 - 96
Optimum temperatures - p. 81
Osphronemus goramy - p. 40, 46 - 47
Overflow channels - p. 20 - 21
Oxidation - p. 85
Oxygen - p. 14, 19, 83 - 88
Paddy culture - p. 179
Parallel ponds - p. 22 - 23
Pectoral fins - p. 33
Pelvic fins - p. 33
Pen culture - p. 177 - 179
pH - p. 89
Phosphates - p. 99 - 100
Photosynthesis - p. 84
Phytoplankton - p. 84
Pituitary gland - p. 142
Plankton - p. 25, 36, 83 - 84
Planning - p. 11 - 52
Polyculture - p. 28 - 30, 45, 108
Poison - p. 171
Pond bottom - p. 59
Pond preparation - p. 79
Pond site - p. 58
Predators - p. 19, 121, 171 - 172
Preservation - p. 157
Protein - p. 3 - 5
Protozoan diseases - p. 167
Pseudomonas punctata - p. 167
Puntius gonionotus - p. 47 (also P. javanicus)
Quicklime - p. 80
Respiration - p. 83
Rivaldi valve - p. 61 - 62
Rohu - p. 40, 45
Rosary ponds - p. 22
Run-off - p. 13
Salting - p. 157 - 162
Saprolegnia - p. 166
Sealing pond - p. 77 - 78
Secchi disc - p. 91
Seines - p. 150 - 151, 155 - 156
Serranochromis robustus - p. 166
Silt - p. 74
Siltation tank - p. 74
Silver carp - p. 2, 29, 40, 43
Siphon - p. 61
Site selection - p. 11 - 13
Size of ponds - p. 23 - 25
Slope - p. 17 - 18, 55 - 59, 77
Sluice - p. 20, 64 - 65
Smoking - p. 162
Snakeskin gourami - p. 40, 49, 138
Soft water - p. 15, 74
Soil - p. 15, 74
Spawning - p. 130
   Induced - p. 130, 141 - 146
   Natural - p. 130 - 140
Spoiled fish - p. 163
Springs - p. 13
Stocking - p. 107, 109 - 114
   Density - p. 107
   Rates - p. 108
Stripping - p. 145 - 146
Superaturation - p. 99 - 100
Surveying - p. 55
Tawes - p. 39, 47, 48, 139
Temperature - p. 81
Threespot gourami - p. 40, 49, 138
Tilapia - p. 2, 29 - 31, 40 - 43, 109, 119, 133 - 134
Tilapia macrochir - p. 40
Tilapia melanopleura - p. 40
Tilapia mossambica - p. 2. 40, 42
Tilapia nilotica - p. 2, 40, 42
Topography - p. 17
Trash fish - p. 163
Trichodina p. 168
Trichopterus pectoralis - p. 40, 49
Trichopterus trichopterus - p. 40, 49
Turbidity - p. 25, 90 - 92
Turn-down pipe - p. 62
Walls - p. 19, 54, 74
Water quality - p. 14
Water supply - p. 13
Worm parasites - p. 169
Wells - p. 14
Yolk sac - p. 36
Zooplankton - p. 84