The present study was performed to evaluate the efficiency of supplementation of two Bacillus trains (Bacillus amyloliquefaciens and Bacillus subtilis) on the performance of white shrimp (Litopenaeus vannamei). The control treatment had no addition of Bacillus and two other treatments were supplemented with either B. amyloliquefaciens or B. subtilis in the culture tanks, at density of 10⁵ CFU/mL. Fifty shrimps with an average initial weight of 1.01g were stocked in the 120-L tank at salinity of 16 ppt and each treatment had three replicates and lasted for 60 days. Results indicated that survival and growth performance of shrimp in the two supplemented Bacillus groups were significantly better (PVibrio and higher concentrations of TAN and NO₂ as compared to those of the Bacillus addition treatments. When comparing two Bacillus trains tested, supplementation of B. subtilis to the culture tank seemed to be more effective than B. amyloliquefaciens as expressed by shrimp had higher survival and growth rate and better water quality although there was no significant difference (p>0.05). Therefore, Bacillus subtilis can be considered a good probiotic bacteria for applying in shrimp culture to promote the growth rate of shrimp and improve water quality in the rearing tank.