The Culture of Tilapia Nigra (Gunther) in Ponds II-The Influence of Water Depth and Turbidity on the Growth of Male T. Nigra

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van Someren, V.D.; Whitehead, P.J.
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In ponds which have been stocked with equivalent numbers of male T. nigra, and which have shown comparable survival rates over a period of six months, the growth of fish has been markedly better in those ponds in which the water is shallow (average depth one foot), as opposed to deep (average depth two feet), and clear as opposed to turbid. At the two extremes of shallow / clear and deep/turbid, the fish in the former showed an advantage of 26 per cent greater length, and 43 per cent greater weight at the end of the six months. Analysis of environmental factors have shown that the main feature responsible for these differences is almost certainly water temperature. Ponds which are shallow and clear maintain their water at higher temperatures for longer each day than deep or turbid ponds. Such higher temperatures will in themselves induce faster growth directly, as is well known for other species of fish. At the same time, however, other factors are probably operative; shallow clear ponds will allow of greater light penetration, and hence better diatom growth on the bottom mud, diatoms
East African Agricultural And Forestry Journal, 25, p. 66-72