and construction of the cages; the standardization of cage materials (which
should ideally be sturdy, attract less fouling organisms and be nontoxic
both to the fish and consumers) and the proper layout and positioning of
the cages in water bodies.
Both in Latin America (ADCP 1978) and in Africa (ADCP 1980), tilapia
cage culture has been selected as a priority culture system in the research
programs of the future United Nations Development Programme (UNDP/
Food and Agriculture Organization of the United Nations (FAO) Aquaculture
Regional Centres. The research needs identified include: design of cages
suitable both from the functional and economical points of view; testing
of construction materials; design of rafts, floats, anchors and other require-
ments for cage installations; feed formulation and preparation; feeding
procedures; biology of the cultured stocks; economic evaluation and possible
fish health hazards and their control.
Attention should also be given to the effects of cage culture on the
environment. In particular, estimates of the optimum cage volume relative
to that of the water body should be obtained, both for closed and open
aquatic systems. These should become the basis for the rational future
development of tilapia cage culture. Finally, a new methodology for the
routine mass production of fry and fingerlings should be developed.Prospects- CULTURE POTENTIAL OF THE MAJOR TILAPIA SPECIES
Tables 16 and 17 summarize the culture potential in terms of production
of the four main cultured species; S. mossambicus and T. rendalli have been
both mostly raised in extensive and semi-intensive systems and S. aureus
and S. niloticus in intensive systems. This probably reflects the geographical
distribution of their cage culture (see Table 1) and makes it rather difficult
to assess the real future potential of each of these four tilapias for cage
culture on a worldwide basis. Further experiments will be required, especially
for the semi-intensive cultivation of S. aureus and S. niloticus and the
intensive cultivation of the other two species.
As the culture system is progressively intensified, growth and production
increase, but, in the presence of moderate to dense algal blooms, relatively
high values are attainable for S. aureus even in extensive systems. Indeed
these results are even better than for the obher tilapias in more intensive
systems. Therefore, the extra cost of feeding should always be weighed
against the production obtainable from natural foods for a given species
and location. Such comparative data are lacking for S. niloticus which might,
also provide good results with algal blooms.
The current relative production potential for the four species may be
summarized as: for extensive systems, S. aureus > S. niloticus > S. mossam-
bicus; for semi-intensive systems, T. rendalli > S. mossambicus and for
intensive systems, S. aureus > S. niloticus > S. mossambicus. T. rendalli
fed with Alocasia leaves and wheat bran has shown a relatively good produc-