Aquaculture of nile tilapia (oreochromis niloticus linnaeus, 1758) with an assessment of its economic benefits in the lake Victoria basin, Tanzania

Fish stocks in Lake Victoria have drastically declined while the demand for fish has exponentially increased, leading into inadequacy of fish. Aquaculture has the potential of bridging the widening gap created by the increasing demand. Despite the enormous potential for aquaculture development in the Basin, this sub-sector is still underdeveloped. This thesis examined the aquaculture of Nile tilapia (Oreochromis niloticus) and assessed its economic benefits in the Basin. Assessment on fish pond performance suggests that, despite low fish yield due to poor pond management, aquaculture offers an opportunity for increased productivity. Investigations on diurnal dynamics of water quality parameters showed that dissolved oxygen and un-ionized ammonia were beyond the acceptable limits for fish growth suggesting a need for frequent water quality monitoring in ponds. The effects of integrating fish farming with vegetables on fish growth, yields and economic benefits revealed higher performance from integrated than from non-integrated system, pointing to the importance of integrating fish farming with other on-farm activities. The effects of stocking density on production and economic benefits in polyculture and monoculture systems were assessed. It is suggested that the choice of an optimum stocking density is an important aspect in attaining higher performance in any culture system. Investigation on the reproductive biology of Nile tilapia showed that its early breeding behaviour in captivity is not affected by culture system and thus, its production can be improved through proper pond management. The practical application of the results is discussed in detail in each chapter and a synthesis is presented at the end of the thesis.