In the present study effects of adding the probiotic Pediococcus acidilactici (PA), on growth performance, feed utilization and carcass composition of Nile tilapia, (Oreochromis niloticus) fingerlings were investigated. Four experimental diets were formulated, as isocaloric (4417.23 Kcal/kg diet), containing 25% crude protein (CP), and 23%  crude protein (CP), each was either addition or not with Pediococcus acidilactici (PA) at 1g /kg diet (T1, T2, T3 and T4), respectively and fed to monosex Nile tilapia, (Oreochromis niloticus) fingerlings with average weight (2.60 ±0.01g/fish). Total of 240 fingerlings were random distributed in four treatments, triplicate groups each with twenty fish/ aquarium. The experiment period was lasted for 71 days. The results indicated that fish fed low level of crude protein (23%) in tilapia diet without Pediococcus acidilactici recorded the worst values of growth performance and feed utilization parameters. Also, fish fed with P. acidilactici presented higher weight gain and specific growth rate (SGR) and the best feed conversion ratio (FCR), protein efficiency ratios (PER), protein productive value (PPV % ) and  energy utilization compared to the control diet. The results indicated that the use of 1× 10⁹ cuf kg-1 dry feed probiotics improved growth parameters and feed utilization in Nile tilapia fingerlings.