In this study the effects of two probiotic bacteria, namely Bifidobacterium animalis and B. lactisin, with the three concentrations of 1×10⁹ (T1), 2×10⁹ (T2), and 3×10⁹ (T3) CFU 100g^-1, on growth performance and survival of rainbow trout larvae with initial body weight of 0.538 ± 0.197g were evaluated in comparison with the control (without probiotic) during a 60-day study. This research was designed with a control and three experimental treatments with three replications. Among all the treatments, T1 showed the highest growth (p<0.05). In addition, a significant difference was observed between experimental treatments and the control with regard to growth and nutritional parameters and also body composition (p<0.05). The survival percentage of the larvae was significantly higher in experimental treatment in comparison with the control. The results of this study showed that the use of B. animalis and B. lactis could improve growth performance and decrease mortality rate during rainbow trout larviculture.