Growth of small and medium scale pond aquaculture in East Africa has been limited by cost of feeds and management strategies related to lack of appropriate technologies. The objective of this on-farm trial was to propose the most profitable and practical pond management options based on our combined experiences and to test them on farms to evaluate their profitability and repeatability. The trials began in December 2020, and were conducted at eight farms in Central, Eastern and Western provinces, Kenya. All ponds, including lined ponds were treated with agricultural lime prior to stocking. Ponds were then stocked with sex reversed male nile tilapia Oreochromis niloticus (2.5- 4.5 g) at 3m-2 followed by an addition of catfish Clarias gariepinus at 0.3 m-2 after the second month. All treatments used fertilizer (DAP and urea) to produce natural food for the tilapia. Three supplemental feeding protocols were tested: TRT1, wheat bran (about 16% crude protein (CP), cost $0.25 kg-1); TRT 2, low protein feed (25%CP, cost $0.85 kg)-1; and TRT 3, high protein feed fed at half rate (30-32%CP, costing over $1 kg-1). Fish were fed twice daily, according to a feed table and fertilizers applied weekly, until May, then suspended. No aeration was used and water was managed to be static, except for topping off from evaporation or seepage.
The higher protein feed given at half ration (TRT3) resulted in the most reliable net revenues per are (100 m2), but some farmers found the bran plus fertilizer treatment to be highly profitable. However, leaky ponds managed under the bran plus fertilizer protocol did not perform well. Other reasons for low performance included low survival due to bird depredation (Farm 4); and low fish recovery due to occasional water overflows and incomplete pond draining (Farm3). Previous surveys that showed very low to negative profits from pond fish farming were likely based on farmers who purchased the less expensive floating feeds and fed at high rates, with no fertilization, as evidenced by TRT2 in this trial. Farmers need to be taught to only use feed tables as a guide and to be conservative on feed use. The individualized farm advising provided during the trials helped participating farm managers increase their understanding of pond management, feeding and water quality management. Some owners had never made any profits previously.