Aquaculture production in Tanzania has increased in recent years, responding to an increased demand for fish, partly because of an increasing population and declining catches of wild fish. However, the current aquaculture production is still low, dominated by small scale farming systems, that are struggling with a number of challenges such as lack of improved fish breeds, feeds, technical skills and low adoption rates. This thesis aims to assess the status of fish pond farming with a focus on integrated agriculture and aquaculture (IAA) systems in Tanzania, and to provide guidance on how these systems could be further developed to help local farmers to diversify their food production and income generation. Methodologies included field observations, interviews, structured questionnaires, field experiments and laboratory analyses. Two field surveys in six districts and seven regions of Tanzania provided insights on the current status and the contribution of small-scale pond farming and IAA to household income and food production. Differences between IAA and non-IAA fish farming practices, and their influence on farm productivity and profitability were assessed. Also, opportunities, constraints and farmers’ future plans for fish farming were explored. Two field experiments were conducted on selected IAA systems identified during the surveys. One assessed the effect of including amaranth (Amaranthus hybridus) waste in locally produced fish feed on the yield of Nile tilapia (Oreochromis niloticus). Another investigated how the combination of different vegetables (A. hybridus and Brassica rapa pekinensis) and stocking densities of O. niloticus affected the water use efficiency, need for synthetic fertilizers and overall farm productivity and profitability. The results show that small scale fish farming contributed with 13% of the farmers’ income. 38% of the fish was used for consumption and the remaining part was sold, contributing to both food security and livelihood diversification. Integration of tilapia and vegetables was the most common type of IAA system applied. Local feed ingredients contained medium to high content of crude protein, with high fat content in some animal by-products. The fish yield from the IAA ponds was 60% higher compared to non-IAA ponds because of a more frequent use of on-farm resources and better management. The net income from IAA ponds was 175% higher compared to non-IAA ponds, due to reduced costs and higher yields. Major constraints included water problems, lack of technical skills and good quality fish seeds and feeds. Overall, fish farmers had a positive attitude towards fish farming and the majority were willing to continue with fish farming, with IAA farmers being more positive than non-IAA farmers. The use of amaranth wastes as a fish feed ingredient in a tilapia-amaranth integrated system did not affect the fish growth and yield, but rather improved the feed conversion ratio. The multiple use of water in integrated tilapia-vegetable systems increased the water use efficiency and reduced the need for synthetic fertilizers. Although water from high fish stocking densities increased the vegetable yield, the overall farm productivity in the IAA system was negatively affected because of low fish growth and survival rates. Since agriculture is already popular and fish farming is expanding, promotion of IAA systems could provide an entry point for an increased adoption of aquaculture among rural farmers.
Keywords: Smallholder farmers, Oreochromis niloticus, Amaranthus hybridus, food production, household income diversification, water use efficiency, farm net income