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Aims: To determine the profitability of using a commercial tilapia feed to produce three different size ranges (1.0-1.9, 2.0-2.9 and 5.0-5.9 g) of Nile tilapia, Oreochromis niloticus fingerlings in hapa-in-pond system. Study Design: Completely randomized design. Place and Duration of Study: The Aquaculture Research and Development Centre (ARDEC), Akosombo, of Water Research Institute (WRI) of Council for Scientific and Industrial Research (CSIR), Ghana, from March to May, 2020. Methodology: Fish growth study was carried out in three (3) fine mesh netting hapas, each of dimensions 5.0 x 2.0 x 1.2 m. Nile tilapia fry at initial mean weight 0.03 ± 0.01 g were stocked at a density of 50 fish m-2 and they were fed at 20 % body weight five times daily. The feeding of the fish continued until those in all the 3 hapas attained a mean weight of at least 5.0 g. Then the experiment was terminated and all the survived fish in each hapa were harvested, counted, and their individual body weights were measured. Growth performance indicators and profitability of producing the various size categories (1.0-1.9, 2.0-2.9 and 5.0-5.9) were determined. Results: The fry attained the target size ranges of 1.0-1.9, 2.0-2.9 and 5.0-5.9 g in 4, 6 and 9 weeks respectively. There were significant differences (ANOVA, P = 0.03) among final mean weights, weight gains, feed intakes, daily weight gains, feed efficiencies and harvested biomass among all size ranges, with those of 5.0-5.9 g being significantly higher (Tukey’s HSDT, P < 0.02). Sizes of fingerlings produced correlate positively with cost of feed used. The profit indices ranged from 2.57 to 10.22, with the highest recorded in the 1.0-1.9 g fingerlings and the least in those of 5.0-5.9 g. Conclusion: The results indicated that, at the current Nile tilapia fingerlings cost and the time taken to produce the various size categories, the 1.0-1.9 g production is the most profitable.

The study determined the impacts of fish cage farming on the gorge area of Lake Volta. Water and sediment samples were collected from six sites in the Lee Cage Farm; four from sections with cages and two from about 1300 m upstream of the farm which served as the control. Water quality variables monitored were pH, temperature, dissolved oxygen, nitrate-nitrogen, ammonia-nitrogen, orthophosphate, faecal coliforms and total coliforms. Variables monitored in the sediment were organic matter, total carbon, total nitrogen and total phosphorus. There were variations in water quality between the farmed and control sites but the differences were not significant (p > 0.05). The mean counts of total coliform in the water ranged from 940 - 3318 cfu/100 ml while faecal coliforms ranged from 113 - 552 cfu/100 ml at the farmed site. The mean total coliform count at the control site ranged from 837 - 6960 cfu/100 ml while the faecal coliforms ranged from 48 - 120 cfu/100 ml. Therefore, there was significant variation between the faecal coliforms count at the two sites (p = 0.046). The results suggest that the general microbiological quality of the water at the study area was unacceptable.