In this study 14 bacterial strains isolated from gastrointestinal tract of black tiger shrimp (Penaeus monodon) was investigated for their probiotic potential. The results showed that 6 strains namely S1 S3 S6 S7 T4 and T5 were able to degrade 3 nutrient substances including protein starch and lipid among which S3 S7 and S2 were the best tested nutrient-degrading bacteria respectively. Six bacterial strains were unable to lyse red blood cells including S2 S3 T0 T1 T2 and T3. S2 strain showed the strongest antibacterial activity against shrimp pathogenic Vibrio harveyi following an agar overlay technique. Based on environmental tolerance tests S2 and T0 strains grew well under wide ranges of environmental conditions e.g. sodium chloride concentration (0-8%) pH (6-10) and temperature (25-37C). As a consequence S2 strain had the most probiotic potential for shrimp culture owing to no hemolysis of red blood cells inhibition of V. harveyi growth protein and lipid degrading ability and high environmental tolerance for shrimp cultivation. The strain was identified as Micrococcus sp. S2. However additional study focused on immune response nutrient digestibility and growth promotion of the strain should be further performed in marine shrimp.