of research and production in tilapia. A tropical fish species originating from Africa, tilapia it is rapidly increasing in popularity as a species for aquaculture. In a recent international symposium on the species it was predicted to become one of the most important Worldwide aquaculture commodities in the coming decades.
Figure 5. Asia presently produces more than 80% of the World's tilapia but the interest in the species from both producers and consumers is expanding rapidly throughout the World (Data source: FAO 2000)
It has been introduced around the World and is widely cultured throughout the tropics and sub-tropics. Whilst Asia presently dominates production (Figure 5) tilapia is increasingly being grown in environmentally controlled conditions in temperate climes and has proved as well adapted to intensive culture in closed recirculating systems as it is to extensively managed ponds. The Nile tilapia, Oreochromis niloticus is generally considered the best species for freshwater aquaculture (see Figure 6).
Figure 6. O. niloticus has been responsible for recent growth in tilapia production (Data Source: FAO 2000).
The fish has many attributes suited to domestication and culture. These include good flesh quality and flavour, a wide tolerance of different environments, resistance to many common fish diseases, and relative ease of reproduction in captivity.
This ease of reproduction actually represents one of the principal problems in the optimisation of yields in tilapia culture, the fish breeds TOO READILY. Energy is diverted from growth, into the behavioural and physiological interactions between the sexes and into the production of eggs. Furthermore, unwanted reproduction leads to overpopulation, competition for resources and stunting of growth. The most effective solution to this problem is to grow only one sex, preferably males, as they grow faster and to a larger size. There have been numerous technologies developed for this purpose including hybridisation and direct hormonal sex reversal but none have achieved this in a consistently effective, affordable, and environmentally sound way.