A Comparative study of the growth performance of Oreochromis Mossambicus and Tilapia               Rendalli.

The growth performance of Tilapia Rendalli and Oreochromis mossambicus was compared over a period of 12 weeks. A total of 10 Oreochromis mossambicus and 10 Tilapia rendalli fingerlings both with mean body weight of 1.9 g were separately stocked in 375 L glass aquaria feeding on macrophytes. In the second treatment, 10 O. mossambicus and 10 T. rendalli fingerlings with mean body weight of 1.3 g and 0.9 g respectively were stocked in another 375 L glass aquaria feeding on phytoplankton. A third experiment was set up and contained 10 Oreochromis mossambicus and 10 T. rendalli both with mean body weight of 0.9 g fed on pellets in fibreglass tanks. During the experiment water quality parameters were monitored on a weekly basis and the mass of the fish was measured at three week intervals. Tilapia rendalli feeding on macrophytes obtained a faster growth rate (3.5 g) as compared to Oreochromis mossambicus (2.4 g). However, Oreochromis mossambicus obtained a faster growth rate (4.2 g) as compared to Tilapia rendalli (3.7 g) when feeding on phytoplankton. Oreochromis mossambicus feeding on pellets obtained faster growth rate (6.7 g) than Tilapia rendalli (6.1 g) and had a better food conversion ratio (1.70) than Tilapia rendalli (1.78). This indicates that both species grew significantly faster when supplied with their natural food items. The implication of these results in the context of tilapia culture in South Africa is discussed.