Pond construction


More and more people want to eat fish because it is healthy and tasty. There is a good market for fish and if you manage your ponds well, you can earn a good amount of money by producing the desired quality and quantity.

The Farm Africa fish production training portal gives an overview on:

       1. Pond construction

       2.Pond management

       3. Hatchery and nursery activities

       4. Fish diseases and precautions

       5. Marketing and making money from farming fish

       6. Record keeping

       7. Post-harvest handling and processing

These subsequent training modules are to be used after fish farmers have gone through the training manual. You will be able to know if you are ready to produce fish in ponds.

The modules

Answering the questions will test your knowledge of in the technical aspects of pond management and commercial fish farming. The beginning of farming as a business and not as a hobby depends on putting into practice the various elements you have learned.

In case you need more information, please contact the trainers of Kenya Market-led Aquaculture Programme (KMAP). More information could also be sourced from the aqua-shops (input stores).

Requirements, site selection and preparation

A fishpond is not just a hole in the ground. A well constructed pond can last for over 15 years.  Paying attention to pond site selection, design and construction detail is therefore, the first step to successful pond production. Pond construction needs expertise and specific equipment. If you select a good site, you still may fail if you design your farm poorly or manage it wastefully.

Test the soil before you think of digging a pond

The criteria for site selection

You should select a site taking into consideration the five criterion listed below. This does not mean you must meet every one of the criteria. However, be assured that if you do not meet a particular criteria, your cost of production will rise. If you cannot meet even a few of the criteria, you probably will not make any profit.

Water - Rule of  thumb is that for earthen ponds fish farming one needs year round one liter of water per minute per 10 m² of water. The best situation is to have lots of water for “free,” meaning gravity flow. For ponds, you should have a flow rate of at least one cubic meter per minute for each one hectare of ponds. To maintain production, one has to drain, disinfect e.g. with lime and remove mud from the pond bottom yearly. 

Climate - For commercial purposes, average water temperatures of about 28°C are best, the average temperature should be above 25°C for Tilapia and Catfish. 

Pond size - Bigger ponds are better, but make sure you are able to supply the market continuously. A gentle slope of the land is good, since then it’s possible to 1) drain the ponds, 2) dig the ponds cheaply. 

Proximity to markets - Before you start production, study the market. One can produce many different species of fish, but if there is no buyer, you have a problem. 

Infrastructure - Roads, phones and electricity, although not essential for fish production, are certainly beneficial to a business. If you need to practise an intensive form of fish production, due to other constraints of space or water, you will need access to power. 

Other considerations

Predators  - A “predator-free” site may not remain so for long after fish farming begins. Otters, monitor lizards, pelicans, kingfishers, cormorants and humans are predators that tend to migrate to places where fishing is easy.  It is best to deter predators before they figure out that there are large amounts of fish to catch easily.

Personnel - Some training for prospective staff is necessary at your fish farm. Raising fish requires skills and attention to certain details, which not everybody has.

Access to technical advice - Technical advice can be expensive. Double check any advice and criticism you receive with someone who is qualified (has grown a few tons of fish before). Good consultants admit when they don’t know something.

Fellow fish farmers or competitors - Other farmers can be competitors, but if you use as a rule of thumb that a person would eat in average of 2 kg of fresh tilapia per year, it’s unlikely that you can satisfy the market (this means that a village of 10,000 people would need 20,000 kg of tilapia). Most important is that you agree on a price to sell tilapia with your nearby farmers and nobody should sell below that. You could also buy inputs together and learn from each other’s successes and failures. 

Recommended pond construction criteria

A pond is more than just a hole in the ground; in this chapter we will discuss the different elements that play a role in it.

Pond dykes

The pond’s sides are called dykes. The pond dykes should be well compacted and have a gentle slope.

During construction, one should lay down about 15 cm (length of a Bic pen) of soil at a go which, when compacted will be about 10 cm high. There should be no stumps or debris left within the pond dykes (this will start rotting and consume oxygen, this could also be the place where the dykes will start leaking; stumps could also tear your nets). Soil should be compacted shortly after it is laid to prevent hardening (some soils become rock-like if they are allowed to harden). Pond bottom as well as dykes should be from a thick layer of clay to avoid seepage. 

1.Poorly compacted dykes are weaker and often collapse. When pond dykes collapse during the course of production:

The ponds become shallower which lowers the ponds’ carrying capacity.

There is increased siltation and clay turbidity which negatively affects the water quality.

Mud at the pond bottom can become excessive making it more difficult to harvest ponds.

Therefore: Remove all debris, compact soil after adding every 15cm

As a rule of thumb: the slope of a dyke should be 2:1 meaning a length of two meters there should be one meter of height gained.

2. Increased maintenance costs: Pond construction is expensive. The lifetime of a properly constructed pond should higher up the page it says 15 years with minimum maintenance. 

3. Catfish, by nature, are bottom-dwellers. They tend to dig into the dykes of ponds and create burrows. The degree to which they are able to do so is affected by the amount of compaction of the pond dyke and its slope.  In addition to increased levels of siltation, deep catfish burrows make harvesting with a seine less efficient as the fish have a hiding place. 

Water control

Proper compaction reduces the rate of seepage across the pond dykes and bottom. The only source of water loss from a properly constructed pond should be from evaporation. 

Erosion water: It is important to plant grass over the top of the dykes and divert surface erosion water.

Slope of the pond dyke

The slope of the pond dyke is the gradient of the dyke from the edge of the top width to the inside toe at the bottom of the pond. If the distance from the inside toe to where the top width starts (edge of the pond from above) measures two meters and the height of the dam measures one meter, then the slope for that dyke is 2:1 

It is recommended that pond dykes have a gentle slope of about 2:1. This however, depends on the size of the pond. Larger ponds need to have a gentler slope.

Having a gentle slope is beneficial in that:

1.The gentler the slope, the less there will be erosion because of less impact of the waves and less siltation at the pond. Consequently, the dyke is less likely to collapse. 

2.It is easier and safer to enter into and out of the pond. 

Average water depth

The recommended average water depth is 1 meter for non-aerated static-water ponds. The water depth in the pond should be at least 90 cm at the inlet and no more than 1.2 m at the outlet. 

The maximum water depth for static water pond production is determined by the distance sunlight can penetrate into the water column.

This is because photosynthesis can occur in the water column up to twice the depth the sun’s rays can penetrate. In ponds, sunlight can generally penetrate to a depth of about 30-80 cm depending on the levels of water turbidity. In addition, the sun’s rays warm up the water. Hence, the upper water column in ponds has the best conditions for fish production.

The minimum water depth in a pond should be not less than 60 cm. When the pond water depth is less than 60 cm:

        1.The pond’s carrying capacity is reduced considerably.

        2.It is easy for wading birds, such as the marabou stork and heron to eat your fish. 

        3.Water plants are more likely to grow in shallow ponds. 

        4.It cannot keep a stable temperature and climate for the fish. 

The inlet and outlet


The diameter of the inlet pipe should be less than that of the outlet pipe to prevent overflow from the pond. The inlet pipe should be at least 20cm above the water surface to prevent fish from escaping. 

You should put a fine screen (mosquito net size mesh) at the inlet to prevent fish from outside entering the pond. These could bring in diseases and they also increase stocking density. 

The mesh size of the screen material should be the size of a mosquito net. If you have problems of the net clogging, make it like a bag/looser, so water can flow easier.


Preferably the outlet should be at the other side to the inlet. Make sure you have a big enough diameter for the outlet. The bigger the outlet, the faster you can drain a pond. 

Pond outlets should have an anti-seep collar and an anchor-collar. The anti-seep collar prevents water seepage from the ‘joint’ where the outlet pipe and clay soil meet. 

Anti-seep collars are standard construction principles but have been ignored in most pond construction and most ponds have leaks as a result

The free-board height

The recommended free-board height is 30 cm for the following reasons:

        1.It allows for more free movement of air currents above the pond water surface which improves mixing and oxygenation of the water.

        2.It becomes easy to undertake routine tasks such as feeding, seining, checking water quality and removing dead fish.

        3.There is less surface area for erosion into the pond. However, in ponds of over one hectare a free-board of up to 50cm can be accommodated.  

The pond bottom and ability to drain

The pond bottom should be smooth and firm (well compacted!). Pot-holes/depressions at the bottom provide shelter for fish to hide after ponds have been drained. Such fish, if not removed, will predate upon the new stock. 

Being able to drain ponds completely in between cycles makes it easier and you will have to do less maintenance, which is cheaper in the long run and the pond remains more productive. Preferably, ponds should be able to fill and drain completely by gravity to avoid pumping water, which is costly. 

Ponds and drainage canals should also be constructed above the water table. Ponds constructed below or at the level of the water table, are impossible to drain and dry completely. Drying is important to kill pests and reduce organic matter/mud at the bottom.

NOTE: All it takes is one catfish left in the mud, and the next round of fingerlings stocked in the pond will be eaten by the remaining large catfish. 

Shape of pond

Typically, ponds are rectangular. Rectangular ponds are more practical to construct and manage. 

Pond Preparation

Remove excessive silt from pond bottom

The bottom of the pond bottom should be free of excessive amounts of silt. It should also be dry and firm before filling with water. Over time (years), the bottom mud becomes increasingly anoxic (no oxygen), forming hydrogen sulphide which could kill your fish. 

If there is not so much silt, the bottom can be left to dry until the surface cracks slightly before the pond is re-filled with water for the next cycle. 

The cracks allow air to enter between the mud and aerate it. Alternatively, before the next cycle, you can open the soil with a hoe to aerate in order for organic matter to reduce.    

Screen the inlet and outlet

The objective of screening, is to prevent undesirable substances (fish and fish eggs, inclusive) from entering or leaving the pond without obstructing the flow of water

A well designed pond looks like this:


Pond stocking preparation guidelines

The pond is the foundation for success in fish production. It directly affects yields and returns because of its influence on the following;

        1.The pond carrying capacity.

        2.Water quality and water volume control in the pond.

        3.The number of fish that survive to harvest.

Recommended standards for commercial grow-out ponds

        1.The pond dykes must be well compacted with a slope of at least 2:1.

        2.Remove debris, such as tree stumps, within the dykes.

        3.Average water depth in a pond should be at least one meter (0.8m at shallow end and 1.2m at the deep end. However, when using hapas, recommended average depth is 1.5m.

        4.Inlet pipe should be at least 20cm above the pond water level and properly screened.

        5.Outlet pipe screened correctly with mesh and the size should allow pond draining to be carried out within four hours.

        6.Free-board of about 30 to 50cm depending on size of pond and its dykes planted with grass are recommended.

        7.Having a harvest basin at the deep end is optional but is highly recommended.

        8.The pond should be able to drain completely. The pond bottom should be firm, and with gentle slope (1 to 2%) from the outlet to inlet. An option is to make a small drain canal towards outlet. 

        9.Preferably, the pond should be rectangular in shape.

How to prepare the ponds for stocking

        1.Remove excess mud and dry pond bottom after each production cycle.

        2.Ensure pond is not leaking and is deep enough

        3.Undertake the necessary repairs.

        4.Screen the inlet and outlet.

        5.Disinfect the pond with lime, drain completely.

        6.Ensure there are no live fish left in the pond.

        7.Fill the pond.

        8.Maintain pond record sheets with the details of any management treatments.

        9.Check pond water quality before stocking

Drying of the pond

The preparation for the next crop begins the day after the last fish are harvested from the pond. First of all, the pond has to be completely drained.

The pond is completely dry when all water puddles have been dried out by the sun and the first cracks appear at the pond bottom. Proper drying of a pond will take two to three weeks. It will improve availability of nutrients in the pond bottom, the mud will decompose and most pests, water insects, amphibian larvae (e.g. tadpoles) and unwanted wild fish will disappear. 


Liming has two functions: disinfection and enhancing fertility. If it is not possible to completely dry the fish pond (until the bottom cracks) you will have to use lime to disinfect your pond (including during the rainy season). Lime kills most small creatures (parasites, insects, tadpoles, etc.) which are harmful to your fish, or which might transfer diseases

Liming is necessary when:

        1.The pond soils are acidic, pH 5 and below. 

        2.The pond cannot drain completely. In this case, lime the remaining puddles until the water pH increases to 11. Spread the lime over the pond bottom while paying extra attention to potential hiding places.

After liming, the pond can be filled with water the following day but only stock it when the pH has decreased to below 8.

Fertilising the pond

For tilapia it is important to fertilise the pond, especially at the early stages. The pond should turn light bright green within a week after fertilizing. There is no need to fertilise ponds for catfish grow-out if the fish are fed on nutritionally-complete pellets. This is because all their food requirements are derived from the feed. 

Which lime to use?

Disinfecting = killing everything in the pond, which happens at a pH of 10 or 11. This can be achieved by using two types of lime which can be purchased at most agricultural stores:

        1.Agricultural lime 

        2.Quick lime

 How to apply lime:

Lime for disinfection is preferably applied when the soil is still moist. If there are areas where there are still puddles of water apply more lime on these spots. The right amount of lime is applied to your pond by sprinkling it evenly on the pond bottom, don’t forget the slopes of the dykes! 

Caution: lime is very aggressive, use protective gloves, protective goggles and face masks while applying the lime. Wash off any dust immediately after.

Through fertilization, we provide nutrients on which algae and phytoplankton will grow.

When the pond has approximately 20 cm (9 inches) of water, you can apply fertiliser. If you use inorganic fertiliser, make sure it is dissolved completely in a bucket before you sprinkle it evenly on the water surface. Make sure you splash it into the water and not onto the dykes. If you use dry manure, you can broadcast it directly onto the water surface. When the water becomes green (in 5 to 7 days) you can fill the pond completely up to the desired level.

Too much fertiliser deteriorates water quality and oxygen levels and too little fertiliser makes your algae grow slowly. If the Secchi disk (or your hand) is visible below a depth of 30-40 cm, continue applying fertiliser every week. 

It is highly recommended to use DAP and Urea together.

Dry manure, from chicken, pigs, cattle, goat, sheep etc.

Flushing the pond is best done by first draining about 1/3 of the water after which water is added.

Measure the turbidity after 4 days and decide if it needs fertilisation. You can choose between fertilising every week or every 10 days or even every two weeks – depending on your algae bloom.

Stock the pond as soon as possible after it has been filled.

Summary of guidelines for pond construction and preparation for stocking

The pond is the foundation for success in pond fish production. It directly affects pond yields and returns because of its influence on the following:

        1.The pond carrying capacity,

        2.Water quality and water volume control in the pond,

        3.The number of fish that survive to harvest.

Recommended standards for commercial grow-out ponds

        1.The pond dykes must be well compacted with a slope of at least 2:1.

        2.There should be no debris, such as tree stumps, within the pond dykes.

        3.Average water depth in a pond should be 1m to 1.5m (at shallow end at least 0.8m and deep end at least 1.2m).

        4.Inlet pipe at least 20cm above the pond water level and screened with a properly fitted sock.

        5.Outlet pipe fitted with collar and screened correctly with mesh.

        6.Free-board of about 30 to 50cm depending on size of pond and grass planted on the dykes.

        7.Having a harvest basin is highly recommended.

        8.The pond should be able to drain completely. The pond bottom should be firm, without ‘pot-holes’ and gently sloped (1 to 2%) from the inlet to outlet.

        9.Preferably, the pond should be rectangular in shape.

Recommendations for preparing ponds for stocking

        1.Remove excess pond bottom mud and dry pond bottom, put this on your field.

        2.Ensure pond is not leaking and is deep enough. Undertake the necessary repairs.

        3.Screen the inlet and outlet.

        4.Treat the bottom of the pond with lime, if needed such as if pond cannot drain completely.

        5.Ensure there are no live fish left in the pond.

        6.Fill and fertilise the water or pump water from a green pond.

        7.Maintain pond record sheets with the details of any management treatments.

        8.Check pond water quality before stocking.