A study was conducted to Comparative study of the effect of dietary Prebiotic (Saccharomyces cerevisiae) (0.2%), Acidifier (0.15%) and prebiotic with acidifier on growth parameters of rainbow trout grower's (150 ± 5 g) compared to fish fed an un-supplemented diet, in three replicate. The prebiotic and acidifier was mixed with a particular commercial diets. The fish were evaluated at days 10, 20, 30 and 40 of being fed by the experimental diets in order to obtain, growth rate, total length, feed conversion rate, feed intake rate and survival rate. The result indicated that, significant differences in feed intake were found between different groups (P <0.05) and the prebiotic group had the highest feed intake. During this study, Fish fed prebiotic and prebiotic with acidifier displayed significantly increased (P <0.05) special growth rate compared to the control and acidifier fed fish. Fish fed prebiotic displayed significantly decreased (P<0.05) feed conversion rate compared to the control and acidifier fed fish. Fish fed acidifier displayed significantly decreased (P <0.05) total length compared to other groups. During testing, no casualties among the treatment groups and control fish were observed. The survey results showed that the rate of 2 kg ton-1 of prebiotic can improve fish growth parameters in comparison with other groups.
