Effect of feeding times and stocking size on growth and food conversion rate of rainbow trout in brackish water

An experiment were conducted to evaluate The effect of feeding frequencies and stocking size on growth and feed conversion ratio (FCR) of rainbow trout (O. mykiss) in brackish water for 102 days. Three stocking sizes (10, 25 and 40 g/fish) of rainbow trout and three feeding frequencies (feeding fish twice, three times and four times per day) were examined as the same time. Fish were fed at a restricted feeding program according to the rainbow trout standard table in the definite times during the light period. The results showed that in the group with 10 g initial weight increasing the feeding frequency, some growth factors like final weight, daily growth, and weight gain. But the other factors such as food conversion rate (FCR) and specific growth rate (SGR) decrease. It means in this group (10 g) two times feeding per day is not enough for an acceptable growth rate. In the two other groups with (initial weight 25 and 40 g) although by increasing the feeding frequency, some growth factors a little increase but these differences in 95% level (p≤0.05) are not significant. Therefore in rainbow trout culture with initial weight at least 25 g two times feeding per day was enough. The results of carcasses analysis of fish, showed that by increasing the feeding frequency there were no significantly difference at 95% level between the body compositions in all of treatments. With connivance of feeding frequencies, the best FCR was in the group with 10 g initial body weight and there was not any significant difference in SGR. So according to the results, it suggests that fish should be stocked with 10 g initial body weight.

Iranian Fisheries Science Research Institute

Published