Effects of varying levels of fish oil on growth performance, body composition and haematological characteristics of Nile tilapia Oreochromis niloticus (L).

reochromis niloticus with an average weight of 25.7g.were reared in glass aquaria at a density of 15 fish / aquarium for a period of 16 weeks. Four artificial diets with control diet containing (0%), 3%, 6% and 9% supplemented fish oil were used in the present study, to investigate their effects on growth, body composition and haematological properties of Nile tilapia. Results revealed that the best growth (54.4g/fish) was obtained with the 9% supplementary lipid followed by the diets containing 3% fish oil (48.7 g/fish), control diet (47.3 g/fish) and 6% (41.1 g/fish) supplemented fish oil. Furthermore, the highest percentage of weight gain (28.7%) and the highest specific growth rate (0.78%) were obtained with the 9% supplemented fish oil. Biochemical analysis of whole fish bodies indicated that moisture, ash and protein contents were unaffected by the lipid levels in the diet, lipid content was increased with the increased lipid level. Results of the present study show that serum cholesterol and glucose levels as well as haemoglobin content were affected significantly with the lipid levels. Total serum protein (TSP), total serum albumin (TSA) and total serum globulin (TSG) studied show that the (TSP) and (TSG) were not significantly (p > 0.05) affected by lipid levels, while the (TSA) was significantly (p< 0.05) affected by lipid levels. Also results revealed that R.B.Cs, W.B.Cs counts, Hb and haematocrit (P.C.V) were not significantly affected by lipid levels among all treatments. Results of the experiment show that protein, glucose and cholesterol for fish fed diet containing the highest supplemented lipid (9%) level were significantly different (p< 0.05). Based on the obtained results, it could be concluded that an artificial feed with 3% and 9% supplemented fish oil is sufficient for feeding O.niloticus without any adverse effects on growth performance, body composition and haematological properties.