Influence of pond fertilization and feeding rate on growth performance, economic returns and water quality in a small‐scale cage‐cum‐pond integrated system for production of Nile tilapia (Oreochromis niloticus L.)

The effects of pond fertilization and feeding rate on growth, economic returns and water quality were investigated to develop a low-cost cage-cum-pond integrated system for production of Oreochromis niloticus (L.). Hand-sexed male fingerlings averaging 19±0.39 and 32±0.69 g were stocked in cages and open ponds at 150 fish cage−1 and 2 fish m−2 respectively. Fish were cultured for 114 days in five triplicate treatments. Cages were installed into ponds and caged fish were fed a 24% protein diet at 3% (T1) and 6% (T2) body weight day−1 (BWD) without pond fertilization, and 6% BWD with pond fertilization (T3). The open water in the fourth treatment (T4) was not stocked but contained caged fish, which were fed 6% BWD for the first 57 days followed by 3% BWD for the remaining period. Ponds in the control (T5) had no cages and were neither fertilized nor open-pond fish fed. Feeding rate and pond fertilization significantly (P<0.05) affected fish growth, profitability and water quality among treatments. Fish growth, feed utilization, fish yield, water quality and profits were significantly (P<0.05) better in T3 than the other treatments. It was concluded that fish production and economic returns were optimized at 6% BWD in fertilized ponds.