Methods For Controlling Tilapia Reproduction

The following seven methods are used to control tilapia reproduction.

1. Periodic harvesting of tilapia fry and fingerlings with nets to reduce competition for food.

• effective in small ponds.
• labor intensive.
• requires little skill.

1. Separation of sexes after an initial growth period (monosex culture).

• males grow faster than females.
• difficult for large ponds since large numbers of fish are needed and the process is slow.
• mistakes are made and sexing is about 90% efficient.
• requires trained labor.

1. Stocking hybrid “all-male” fingerlings.

• males grow faster than females.
• requires pure strains of broodstock.
• requires special hatchery facilities and skilled labor.
• hybrid fingerlings are expensive to produce.

1. Culture in cages which are suspended above the pond bottom.

• spawned eggs fall through the cage mesh and die preventing overcrowding.
• cage materials may be expensive.
• requires intensive feeding with high quality ration.

1. Culture at very high densities in ponds or raceways.

• crowding reduces the urge to reproduce.
• intensive feeding with a high quality ration is required.
• good water supply must be available.
• requires electric, gas or diesel aeration devices.
• requires skilled management.

1. Stocking predacious fish as fingerlings or adults in the tilapia pond.

• controls excessive reproduction.
• produces two different kinds of fish.
• large tilapia must be stocked initially or they will be eaten.
• often difficult to get adequate numbers of predator fingerlings

1. Feed tilapia fry with male hormones to produce “all-male” fingerlings.

• hormones are difficult to obtain.
• hatchery facilities and skilled labor are required.

e. Harvesting

Harvesting of stocks is usually done after three to four months culture period. However, other operators depend their harvesting on the size of fish that depends also in the size preference of the target market. Others hold their harvesting if the prevailing market price is low.

1. Selective harvesting – is the traditional way of harvesting tilapia.

It is usually done in undrainable ponds using a gill net, cast net and seine net. The gear and mesh of the net is selective, such that the smaller fish passes through and retained in the pond. In this particular situation, stocking can be done only once and after four months, selective harvesting started.

Repeated harvesting every two to three weeks can be made.

2. Total harvesting – in drainable ponds, total harvesting of fish stocks after three to four months is done. Ponds are totally drained and fish are confined in the catch basin where the fish are caught by seine net. Fish left in some parts of the pond are picked up manually. In some cases, ponds are partially seined first before total draining such that total harvesting by draining is easier.

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