Cut costs by using mud to make fishponds

If well designed and constructed, earthen fishponds can last longer than those made using plastic liners.

Mixing soil with lime (left). Preparing mud for plastering (right).





One of the persistent problems facing fish farmers is how to stop the loss of water from their fishponds. Farmers who cannot afford to buy UV treated Low Density Polyethylene (LDPE) with a thickness of 1/2 mm can overcome this problem if they adopt an alternative method of making earthen ponds. They can hold water without the use of liners. This method needs some experience and labour, but if properly done, the mud keeps the water in the pond. Here we give a step-by-step instructions but farmers must consult fisheries experts before making their fish ponds.


You need;

Photos: ACORD

1. Red soil without stones (murram)

2. Agricultural lime

3. Water

4. Fishpond area measuring 300 metres squared

5. Labour

Process

Since different farmers may want different sizes of fishponds we recommend the following measurements:

• Mix the lime with red soil at the rate of 1: 20

• Mix the lime and red soil thoroughly, then add water to make a fine, sticky and thick paste similar to the one used to make mud houses.

Mud is spread (left), a thin mud paste is smeared and water added to avoid cracking (right).

• Stick the paste on the surface, the bottom and the sides of the pond. The paste should be 4 inches in thickness.

• To smoothen the surface of the pond, mix the red soil and the agricultural lime and water into a thin paste at a ratio of 1:5, (again a fisheries expert may help here) and smear it over the surface to eliminate all spaces that might have been left during the initial plastering.

• Ensure the surface does not dry by continuously sprinkling with water as you smoothen the surface of the pond.

• Make sure you do not step on the completed area of the pond as you work.

•Fill the pond with water to the brim immediately you finish plastering and keep on monitoring the water level.

NOTE:  Agricultural lime is used because it has double advantages of making the soil sticky, besides making the pond alkaline and more conducive to fish.


Important tips on how to manage fish


The fingerlings should be sourced from a reputable breeder. Many farmers stock mixed sex tilapia, but this may not be the best because they normally breed early and very fast and overpopulate the pond. The fish cannot grow to the suitable market size because of overcrowding. Fish that is small in size cannot attract a good market. The market size in Kenya is normally above 200g.

Feeding is important

Farmers who want to avoid this problem of overcrowding are advised to stock monosex (males only) Tilapia fingerlings. These grow to good market weight fast because they cannot breed in ponds and are harvested all at the same time. For instance if a farmer stocks 1000 fingerlings in a 300 metres squared fishpond, and feed them well, they will normally mature after the 6th to 10th month depending on the water temperature and management. The market price ranges from between KSh 250 to 300 per kilo, therefore a farmer can easily make an income of KSh. 90,000 in a year.


In fishpond farming, some protein comes from the algae in the fishpond (resulting from proper pond water fertilization) and the rest from external feeding with supplementary feed concentrates with about 26% crude protein. For most fish, feeding twice a day is sufficient – at about 10 am and 4 pm. If it is done earlier than 10 am in the morning, the water is a bit cold and oxygen levels are low so this is not a good time to feed the fish. If you feed at the same time and at the same place in the pond every day, the fish will learn to come for the feed.


Challenges


• Poor handling of fish is a major cause of both bacterial and parasitic infections.

•  Transporting of fingerlings/ fry (very young fish) from one place to another without proper care can spread diseases and parasites.

• Over crowding of fish in a pond.

• Pollution due to high levels of ammonia parasites causes fish deaths in large numbers. Human faeces may be a source of gut parasites especially for common carp.

• Damage of fish by predators lead to secondary bacterial or fungi infections. The predators especially birds and mammals play an important role in life cycles of certain parasites.