Tilapia has been successfully farmed in tropical regions as it is hardy and can withstand intensive farming (high population density). It breeds easily, is resistant to disease, withstands handling and grows quickly. It can be reared in earthen ponds, concrete tanks or in cages.
Tilapia is the second most farmed fish in the world after carp and ahead of salmon. China is the main producer, with 1.1 million tilapia in 2008 and Africa is the main consumer with 950 000 tonnes consumed per year.
The most frequently used species in aquaculture are the Nile, Mozambique and Aureus tilapia. They have small stomachs and are fed up to four times a day with small quantities of mostly agricultural by-products (oil cakes made from oil-producing plants, cotton or corn), organic fertiliser (liquid manure) and granules. The fingerlings need more protein than the adults and receive additional animal by-products (meat meal, blood meal, fish meal and fish oil) and vitamins.
© Shutterstock / konmesa – Tilapia farming in Thailand
Mature females can lay eggs every three to four months (from the 12th week in the case of the Nile tilapia). They lay their eggs in nests made by the males, then carry the fertilised eggs in their mouths until they hatch. They then keep the fingerlings close by until they are big and strong enough (10 millimetres). To boost reproduction, one male fertilises three females. Water temperature is also scrupulously monitored, as tilapia only breed at a minimum temperature of 22°C. Large fingerlings are separated from smaller ones in the breeding area to prevent cannibalism.
Growth varies according to the variety, sex and breeding conditions (density of fish, food, water temperature, saltiness of the water). In intensive farming, the Nile tilapia gains around 1 g to 2 g a day in water kept at 25°C. The results are higher for males and improved breeds kept with a low population density at 30°C. After seven months in water, these fish can weigh up to 650 g whereas with a high population density, the fish only weigh 300 g. Once the fish are harvested, they are packed in ice straight away to be transported to wherever they will be sold fresh or processed. As they have a long shelf life, tilapia are particularly valued in processed meals such as fish fingers.