this study was conducted to evaluate the effect of prebiotic short saccharomyces cerevisiae yeast cell wall (ycw) on growth , nutrition and survival rates , blood indices of rainbow trout (oncorhynchus mykiss) were studied . 600 pieces of salmon with an average weight of (1 ± 20) g 4 treatments and 3 replications (each replication 50 pieces of fish) groups. treatments 1, 2, 3 and 4, respectivel...