Probiotics effect with dietary supplemental feed on growth and yield of male tilapia (Oreochromis niloticus) in floating cages placed at Dekar haor of Sunamganj for 120 days was assessed. Four treatments viz T₁ (Safegut), T₂ (Biogen), T₃ (Super biotic) and T₄ (control) each with three replicates were used in the experiment. Tilapia were stocked in cages at a density of 40 no. m^-3 with the average initial weight of 14.23-16.44 g and they were fed with commercial floating feed at a decreasing rate of 10-5% of total biomass thrice daily. Feed was supplemented mixed with probiotics at a rate of 0.5 g kg^-1. Higher growth (289.56±14.14g), survival rate (96.91%), yield (10.67±1.7 kg m^-3), net profit (BDT 845.25±86.8 m^-3) and lower food conversion ratio (1.13) were obtained in T₁ than those of other treatments, which were 4-5 times higher than the earthen pond production of tilapia in Bangladesh. The lowest growth, survival, production and higher FCR were found in control treatment where no probiotics was supplied. Therefore, results of the study suggest that probiotics may be applied to supplementary feed to boost up fish production.