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The inadequate supply of tilapia fingerling is a major limitation to cage culture development in Ghana. Lake-based hapa systems are very efficient in nursing fingerlings although the process can be tricky due to inherent effects of stocking densities and environmental factors. This study aimed at assessing the growth, survival and profitability of Nile tilapia (Oreochromis niloticus) fingerlings of the Akosombo strain reared in nine 1 m 3 Lake-based hapas at different densities. Each hapa was stocked with 2.12 ± 0.14 g sex-reversed tilapia fingerlings at varying stocking densities of 400 fish/m 3 , 800 fish/m 3 and 1200 fish/m 3 serving as treatments T1, T2 and T3 respectively. Each treatment was replicated thrice. Bi-weekly samplings were done and water quality parameters were measured. After the experiment, analysis of variance showed significant differences (p < 0.05) in the weight gained, specific growth rate, profit index and feed conversion ratio among treatments. The T1 fingerlings exhibited the highest specific growth rate (3.28 ± 0.10%/day) and FCR (1.42 ± 0.09) than others. Overall, profit index was affected by stocking density and varied significantly between treatments. Treatment T3 was found to be better for commercial fingerling production because survival rate (91.14 ± 3.23%) and profit index (3.96 ± 0.24) were the highest while treatment T1 recorded the least index of 1.31 ± 0.10. Survival rates ranged between 89% and 91% but no statistical differences were observed among treatments. It is concluded that the stocking densities used had significant effects on the specific growth rate, gain in weight and feed conversion ratio of fingerlings reared in Lake-based hapas. However, in fingerling production, not only profit but also rapid growth needs consideration, hence, T2 is highly recommended 661for nursery rearing of tilapia fingerlings in this system due to the relatively high profit index, growth rate and survival.

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This study analyzed the potential of harvesting eggs and fry at different time intervals for improved seed production of Nile tilapia. Broodstock were put in 3x1m 2 hapas at a sex ratio of 3 females: 1male. Eggs and fry were harvested at intervals of 8 days, 10 days, 12 days and 14 days respectively. The results showed a direct positive relationship between the harvesting frequencies and total seed production, where Broodfish in the 14 days treatment produced the highest total seed output (13979 ± 314) followed by 12 days (10167 ± 248), 10 days (6645 ± 135) and 8 days (4509 ± 112) respectively. The 8 days harvesting frequency consistently recorded zero swim up fry throughout the study while the 10 days treatment yielded the highest egg counts of 4272 ± 127. The specific growth rates and condition factors of females did not significantly differ among all the treatments.

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