This experiment was carried out in two spawning seasons, from August to September in 2019 and 2020 (56 days each season) to evaluate the effect of dietary probiotic Bactocill, Pediococcus acidilactici (1 x 10¹⁰ cell/g) supplementation on diets of broodstock Nile tilapia (Oreochromis niloticus) and its effect on reproductive performance. The experimental design were four treatments groups in four experimental diets in 12 hapas, each group was divided into 3 replicates (n=24: 6 females and 2 males per each hapa). The four groups (D1), (D2), (D3) and (D4) fed on basic diet supplemented with 0.0, 0.50, 1.0 and 1.50g probiotic/kg basic diet respectively. Nile tilapia [72 females with an average body weight (262.53±20.22 g) and twenty-four males with an average body weight (279.39±24.12 g) were distributed into 12 hapas. In the first season (2019), the highest values of the fry production were observed in the fish group fed on D4, while the highest values of the gonado-somatic index, fecundity and relative fecundity were observed in the fish group fed on D3. The results of the second season (2020), the highest values of the fry production were observed in the fish group fed on D4. The highest level of estrogen or testosterone for Nile tilapia broodstock was estimated when fish were fed on D2 containing 0.50 g probiotic/kg diet. The present study recommended the use of probiotic during reproduction spawning season of Nile tilapia broodstocks at a dose of 1.5 g kg^-1 of diet.