The effects of replacing fish oil with corn oil in the diet on the growth performance and biochemical composition of Rutilus kutum (Kamensky, 1901) fingerlings

The high price of fish oil increases the cost of fish feed. So, using vegetable oils can significantly reduce its cost. Therefore, this study was investigated the effects of replacing fish oil with corn oil in the diet on the growth performance and biochemical composition of R. kutum fingerlings. In this study, twelve 100-L fiberglass tanks were used, each containing 20 fingerlings (6.05 ± 0.6 g in average weight and 7 ± 0.3 cm in average total length). The fish fed with four diets with the same protein, fat and energy including: T0 (control treatment), 25, 50 and 75% replacement of corn oil (T1, T2 and T3). The fingerlings were fed three times for 8 weeks and based on 3% of body weight. At the end of the experiment, growth rate, physical and chemical characteristics of water and biochemical composition of the carcass were measured. In this study, no statistically significant differences were observed between the treatments in terms of food conversion coefficient, protein efficiency coefficient, specific growth rate, body weight gain, length increase percentage, average daily growth, condition factor, survival rate, initial length, final length, initial weight and final weight (p>0.05). There was also no significant difference between the treatments in terms of carcass moisture and ash (p>0.05). However, significant differences were found in terms of the fish protein and fat among the treatments (p<0.05). Hence, the replacement of corn vegetable oil up to 75% with fish oil does not exhibit any negative effect on the growth performance of R. kutum.