Abstract:

Tilapias, (Oreochromis spp) have become increasingly important as cultured fish species worldwide. However, the problem of overpopulation in ponds, caused by prolific breeding, is still a major constraint in the development of tilapia aquaculture in developing countries. The potential for improved yields through the use of controlled reproduction has provided an impetus for studies in monosex tilapia production. The current strategy is to emphasize production of male-only groups because they have faster growth than females. Production of monosex tilapia has been achieved through the use of androgens to reverse the sex, hybridization between specific tilapia species, chromosomal manipulation and, more recently, through the heat treatment of embryos and larvae. Experiments on breeding and nutrition were conducted in a recirculating, closed system. Water was pumped through a UV unit, a biofilter and a reservoir where it was heated before flowing into 32 L glass aquaria. The water temperature at 25±1.0°C was regulated by an automatic thermostat control. Fish diet is the largest single expenditure in fish culture operations. Since the world fish meal production is declining; alternative sources of proteins need to be identified. We evaluated performance of tilapia on sources of protein which are alternative to high-cost fish meal. Evaluations were performed on growth rate, feed utilization, digestibility, survival and general condition of the fish fed graded levels of animal- and plant-based products.