Pond sizes vary, but what is constant is the depth.
Most farmers think every place with water is suitable for pond construction, which is not the case. The place should have enough water, which should flow by gravity.
But some farmers construct ponds without inlets and outlets, which is wrong. Fish cannot survive under such conditions.
A pond should not be dug in an area prone to floods, if you do so, your fish will be swept away by floods.
A farmers are, therefore, advised to carefully selects a good site.
A good site should have the following:
- A permanent source of water
- Clay soil to hold water.
- The area should allow the proper gravitation flow of water in and out of the pond because the fish cannot thrive in stagnant water. Stagnant water easily gets contaminated.
- The pond should be one metre deep towards the inlet and 1.2 metres towards the outlet.
Pond construction
There are two ways of digging a pond — using a tractor and manually. The average cost of using a tractor to construct a 20×40 metre pond is sh10m.
A tractor takes between two and three days to dig a pond compared to people who take months.
A rectangular pond is easy to maintain, especially in protecting it against silting.
It is also easy to harvest fish from a rectangular pond because you can easily access all the corners.
If several ponds are constructed, they should be parallel to each other, with all water inlets on one side and outlets on the other.
The trick is no pond should receive water from the other because this can easily increase the spread of diseases.
Farmers can prevent silting by planting holding grass such as paspalum on the edges of the pond.
Stocking
This is very important because most farmers do not know the right amount of fish to be stocked in a pond.
Many think they get many fish by stocking heavily, not knowing that each pond has a maximum capacity and once over stocked, they fail to grow.
Advises farmers to always look out for a good variety and stock within 10 days of filling the pond with water.
Fingerlings weigh between 7-10 grammes and 2kg per square metre for catfish is recommended, while for tilapia it is 1kg.
This means that if tilapia weighs 10 grammes, you can stock as many as 100 fingerlings in a square metre. On the other hand, if catfish fingerlings weigh 10 grammes and you need 2kg — meaning you stock 200 fingerlings per square metre.
Fingerlings can be bought from Kajjansi fish research centre or farmers at sh150-sh250 each.
Feeding fish
Fish should be fed on prepared feeds. The feeds should be able to provide the necessary nutrients for growth.
The amount of feeds a fish consumes depends on its body weight. For newly stocked fingerlings, it is usually 5% of its body weight.
This percentage, however, reduces as the fish matures. The feeds rate reduces to at least 1% of the body weight as they mature.
If fingerlings weigh an average of 45 grammes after four to five weeks, the percentage of feed is 3.8%x45 grammes, which totals to 1.7kg.
Well-fed fish will have gained at least 122 grammes by the ninth week. By this time, they should be consuming at least 3% of their body weight which is about 3.7 grammes.
You then multiply feeds per fish by the number of fish in the pond to get the total amount of feeds needed. Feeds must be dry and not mouldy.
We advise farmers to use fish pellets because the fish easily consume them compared to the finely ground feeds.
Qualities of a good site for fish pond
It should have the following:
- A permanent source of water
- Clay soil to hold water.
- The area should allow the proper gravitation flow of water in and out of the pond because the fish cannot thrive in stagnant water. Stagnant water easily gets contaminated.
- The pond should be one metre deep towards the inlet and 1.2 metres towards the outlet.
