Replacement of fish oil with vegetable oils based diets on growth and survival of the Caspian Kutum (Rutilus kutum) fingerlings

Effect of replacement of fish oil with vegetable oils (soybean and canola) based diets were investigated on growth and survival of the Caspian kutum (Rutilus kutum) fingerlings in laboratory cultures. Fish (n=1260) (initial weight and length، 0. 62 mg and 4. 2 mm، respectively) were distributed in six practical diet treatments containing 100% fish oil based diet، 100% canola oil based diet، 100% soybean oil based diet and mixtures (50:50%) of these oils in 8-weeks feeding trial. Results showed that mean final weight of fish fed with canola and soybean oil diets were significantly higher compared to other treatments (P>0. 05); but mean total length of fish was not significant between treatments (P>0. 05). The lowest condition factor was observed in fish fed with mixture of soybean-canola oils diet and this content was not statistically different between treatments (P>0. 05). Feed conversion ratio contents were better in fish fed with canola and soybean oil diets. Survival rates of fish fed with canola and soybean oil diets were higher compared to other mixture treatments، but were not statistically different with fish fed with fish oil diet (P>0. 05). The highest specific growth rate was obtained in fish fed with canola and soybean oil diets (P>0. 05). On the basis of the results، it is recommended that there is the possibility of total replacement of fish oil with vegetable oils without compromising effects on growth and survival of R. kutum fingerlings.