Effect of replacement of Caspian Sea gammarus meal by partial kilka fish meal on growth performance, feed conversion ratio and survival of juveniles of rainbow trout (Oncorhynchus mykiss)

The effects of using different of gammarus meal levels (0, 5, 10 and 20%) instead of kilk fish meal as a protein source on growth performance, feed conversion ratio and survival of rainbow trout (Oncorhynchus mykiss) fingerlings were studied over 8 weeks. Rainbow trout fingerlings (mean body weight 5.48 ± 0.32g) were reared in a completely randomized design with three replications in the same conditions. Based on the results, no significant difference was observed in the final length and weight and specific growth rate among treatments. Increase of gammarus meal in diet led to increase of feed conversion ratio and decrease of survival, but the difference was not significant among treatments. Commercial analysis showed that the cost price of feed increased with increase of gammarus meal in diet, significantly. Thus, results of our study showed that adding up to 10% of gammarus meal instead of kilka fish meal in rainbow trout fingerlings diet is suitable, considering gammarus abundance in the shores of south Caspian Sea and lack of significance in difference on growth, feed conversion ratio and survival.