The main objective of this study was to evaluate the effects of the additional graded levels (0, 5, 10, 15 g / kg diet) of a new commercial probiotic Hydroyeast Aquaculture^® to low crude protein (CP) levels (20 and 25%) in diets of monosex Nile tilapia,Oreochromis niloticus fingerlings for 8 weeks, regarding their growth performance, feed intake and nutrients utilization and carcass composition. Fish with an average initial body weight (7.5 ± 0.001 g) were distributed into eight treatments (three replicates per treatment). Fish in each treatment were stoked at 5 fish / aquaria (90×40×35 cm). The obtained results revealed that the high levels of CP (25%) and probiotic (15 g / Kg diet) had positive significant (P ≤ 0.05) effects on fish growth performance parameters, feed utilization and fish carcass composition (DM, CP, and EC) compared with other treatments, but the interaction between them was not significantly affected on all the above parameters. So, it could be concluded that the high level of probiotic 15 g Hydroyeast Aquaculture^® /kg diet is useful with low dietary CP level (25%) in feeding fish at early age stage for enhancing the production performance of Nile tilapia O. niloticus fingerlings, so this level of probiotic may be led to increasing the economic efficiency at large scale in the fish farms.