This experiment was conducted to evaluate the effect of different levels two commercial prebiotic(Behdam) and probiotic(Moltibehsil) on the growth performance, biochemical parameters of body extract and resistance against the challenge tests of Ctenophryngodon idella for 45 days. This experiment conducted in a completely random design with seven treatments which contain triplicates. Three levels of probiotic and prebiotic (200 mg/kg, 400 mg/kg and 600 mg/kg of ration) were added to the basic diet. At the end of the feeding trial, the results some growth performance indices(including: weight gain, specific growth rate, Thermal Growth Coefficient,  Velocity of growth body weight, daily growth coefficend and Survival rate) on the grass carps larve had significantly difference with control group (P<0.05). Subsequently, elevated Body extract biochemical (AST, ALT and Cortisol) analyses was observed in C. idella fed with probiotic and prebioticcompared to control group (P<0.05). Whiles There were no significant differences in amount of ALP, Glocose, total protein and lysozyme among experimental groups (P>0.05). Also, the addition of Behsam and Moltibehsil to the diet increased larval resistance against the challenge tests and Significant differences were observed in expermentral treatment compar with control group (P>0.05). This study highlighted that the different levels of Behsam and Moltibehsil in rearing of grass carp larvae had positive effects on growth performance and resistance to challenge tests, but had a different effect on body extract biochemical parameters in this fish.