Tilapias (family Cichlidae)

Tilapias

Tilapias (family Cichlidae) are natives of Africa. They have been introduced into a large number of tropical and sub-tropical countries around the world since the 1960s, either accidentally or deliberately. Aquaculturally this group of species has had a rather chequered history. Tropical aquaculturists who experienced considerable problems in controlled spawning of fishes were initially excited by the availability of a species that could breed in almost any type of water body. Being herbivorous or omnivorous, it was comparatively easy to feed the species of this group. They were found to be hardy and could be reared in fresh, brackish and even sea water. Even though the darkish coloration of the fish was not very attractive to some, large fish were well relished when presented under different names such as ‘lake fish’ or ‘bream’.

Because of these favourable characteristics, tilapias were considered ideal species for rural fish farming. In early efforts to develop fish culture at a subsistence level in Africa, oriented to improving the nutrition of rural populations, tilapias were the natural choice, especially in the Belgian Congo (now Zaire). But some of the perceived advantages proved to be real constraints to profitable fish farming, particularly the prolific breeding, which resulted in overpopulation of small stagnant ponds. Ex-perience in Asia in the early days of tilapia farming, after the accidental introduction of Tilapia mossambica in Indonesia, createdopposing reactions in countries of that region. While governments of some countries such as Thailand gave active support to stocking everywater body with this species, others, like India, tried to restrict its culture to prevent possible escape of the species into the major river systems.

Despite some of the advantages of tilapia as candidate species for small- or large-scale culture, it was soon realized that the culture technique for producing marketable fish was not as easy as originally believed. Their early maturation and frequent breeding, especially in tropical climates, affected growth rates to such an extent that special measures of stock management and feeding were found necessary to produce fish suitable for human consumption. Even in areas where small fish were acceptable as table fish, stunted tilapia could be used only as livestock feed.There were very few profitable tilapia farms at that time, and naturally interest in tilapia culture dwindled for some time.

In recent years, the status of tilapia as a culture species has risen again, as a result of efforts by enterprising farmers and aquaculture technicians. Acceptability of tilapias as high-quality fish is spreading. The Nile tilapia (T.nilotica) is grown to a large size (680 g), thenstarved for three days in clean water, filleted and individually quick-frozen to produce a quality product (Avault Jr., 1996). Enthusiasm for the species has become so high that some have begun to describe tilapia as the future ‘aquatic chicken’. Irrespective of whether this is an exaggeration or not, it is clear that workable technologies are now available for raising some of the species or hybrids of tilapia on a profitable basis, even though many problems still remain to be solved (Guerrero, 1994).