Using prebiotic and probiotic as functional ingredients in the aquafeed is a new approach to prevent disease and improve fish production. Thus an 8-week fish feeding trial was conducted to evaluate the effect of commercially available prebiotic Safmannan© and probiotic Actisaf© and mixture of these two (synbiotic) ingredients on growth, lysozyme and oxidative enzyme activities of rainbow trout, Oncorhynchus mykiss . A total of two hundred trout were distributed equally into 4 different groups, each with 5 replicates. A c ommercial diet was used as a control. Prebiotic, probiotic and synbiotic diets were prepared by supplementing the commercial diet with 3 g/kg of the Actisaf © 3 g/K of SafMannan© , and 3 g/Kg Actisaf© plus 3 g/Kg SafMannan© . Fish initial mean weight was 52.4 ± 0.28 gram. Fish were harvested at the middle (week 4) and end (week 8) of the trial. Food conversion ratio, weight gain, survival, conditioning factor, hepatosomatic index, and viscerosomatic index of fish were calculated. There were no significant differences(p>0.05) in the growth, biometrics, and survival of fish fed experimental diets 4 and 8 weeks after the feeding trial. A decreasing trend (around 20 %) in FCR of prebiotic, probiotic and symbiotic diets were observed. Lysozyme activity in plasma of fish fed the control diet was significantly higher than that of fish fed the probiotic at week 8 but there were no significant differences (p>0.05) observed in lysozyme activity between control prebiotic and symbiotic diets at week 4 and week 8. Plasma glutathione peroxidase activity was significantly higher(p<0.05) in the prebiotic and symbiotic diet of fish at week 8. Superoxide dismutase activity of plasma was significantly (p<0.05) higher than control in prebiotic, probiotic and synbiotic at week 8. The present study demonstrates that commercial prebiotic and probiotic at the concentration used in this study do not affect the growth of fish, however significant increase in oxidative enzymes activity of plasma of fish fed pre/pro and synbiotic diets as well as decrease in the FCR suggests that these functional ingredients have a great potential to improve fish health , hence the sustainable aquaculture production of fish.