The present experiments were conducted at the experimental fish culture fiberglass tanks with closed a water recirculation system, belonging to the fish production section, Animal production department, faculty of agriculture, Al-Azhar University, Cairo, Egypt. The experiments lasted for 90 days , using three commercial probiotics (Biogen , Premalac  and Lacto Cel- con) as growth promoters in diets to study their effects  on Growth Performance, Feed Utilization , Body Biochemical Composition and immune of monosex Nile Tilapia (Oreochromis niloticus) Fingerlings . Each one of these probiotics was applied in tilapia basal diets at three levels being 1, 2, and 3 g/kg diet as recommended by the producers. The experiments were conducted in 4 x 3 factorial design and included ten treatments each in three replicates (tank). A total number of 750 sex-reversed all male Nile tilapia (Oreocheromisniloticus) fingerlings (25 fingerlings / tank , 3 tanks for control and 27 tanks for three experiments ) ,each  block included control one were fed to fish basal diet as triplicates and assigned for one of the three tested commercial probiotics , with the same initial average weights and with same average total length. All results indicated that either Biogen or Lacto- Cel - con* at 3 g/kg produced a positive effect on growth and feed utilization of tilapia fingerlings. In addition, the immune responses were substantial in both treatment groups following the challenge with bacterial disease. However, the probiotic Biogen or Lacto- Cel - con* when added to fish diet at 3 g/kg, produced a steady improvement of tilapia growth compared to Premalac. Meanwhile, both were superior than using Premalac as commercial probiotics. Lacto- Cel - con*and Biogen*were clearly beneficial for cultured O. niloticus when administered as a food additive. It is argued that such probiotic has a role in disease control strategies, growth promotion and immunostimulation. Further studies are needed in this field as this strategy strengthens and help understanding the role of probiotics looking for the alternative health management strategy for developing aquaculture productivity.