The objectives of the present study were to evaluate the effects of graded levels of a new commercial probiotic Hydroyeast Aquaculture^® (0, 5, 10 and 15 g/Kg diet) on both sexes of adult Nile tilapia Oreochromis niloticus, referred to treatments No. T₁, T₂, T₃ and T₄, respectively, for males and T₅, T₆, T₇ and T₈ treatments for females, on their growth performance, feed and nutrients utilization and carcass composition for 8 weeks. The obtained results showed that tested probiotic at level of 15 g /kg diet (T₄) and 10 g /kg diet (T₇) for adult males and females O. niloticus respectively, significantly (P ≤ 0.05) enhancing fish growth, feed intake and nutrients utilization, as well as realized slight improving of fish carcass composition. Hence, it could be concluded that Hydroyeast Aquaculture^® probiotic is useful at levels of 15 g /kg diet (T₄) and 10 g /kg diet (T₇) for enhancing production performance of adult males and females Nile tilapia (O. niloticus) respectively, so may be using of this probiotic led to economic efficiency especially, for fish farming and hatcheries.