Getahun, Abebe(PhD)Hailu, Solomon2018-07-092023-11-182018-07-092023-11-182008-07http://etd.aau.edu.et/handle/12345678/7232This study was conducted in Lake Babogaya, one of Bishoftu’s crater lakes in Bishoftu town, to determine the appropriate feeding level for tilapia, Oreochromis niloticus and the impacts of supplementary feed on water quality. A 16.9% crude protein diet, local made feed (Mill sweeping, oilseed cake and chicken dug cake) was fed to duplicate groups of O. niloticus fingerlings (29.70 ± 0.45 – 30.43 ± 0.70 gm) and (120.00 ± 0.56 -122.97 ± 0.54 mm) in cages (1 m x 1 m x 1 m). Fingerlings obtained from Lake Babogaya and stocked at a density of 100 fish/cage. They were feed at 1, 2, 3, 4, and 5% of body weight daily. Water quality parameters, pH, temperature and dissolved oxygen (DO) were measured every month during the culture periods. The results of the experiment revealed that the final weight (224.63 ± 1.23, 223.07 ± 1.23, and 223.40 ± 1.23) and specific growth rate (1.22 ± 0.08, 1.20 ± 0.07, and 1.21 ± 0.06) of the fishes fed at 3, 4 and 5% body weights were similar (p>0.05) but differed significantly (p <0.05) from the final weight (118.30 ± 0.43 and 152.87 ± 0.40) and SGR (0.81 ± 0.08 and 0.99 ± 0.07)of the group of fishes fed at 1 and 2% body weight respectively. Moreover, there were significant differences in FCR of fishes fed at the various body weights (1.76 – 6.33). Survival rate was not affected by feeding level. In addition, pH, DO and temperature of the culture water were not affected by the treatments. The study established the optimum feeding rate for O. niloticus at 3% body weight daily reared in cages. Keywords: Cage, Ethiopia, Feeding Levels, Lake Babogaya, Oreochromis niloticusenCageEthiopiaFeeding LevelsLake BabogayaOreochromis NiloticusThesis