Bangladesh]. Fish. Res., 13(2), 2009: 185-193 Suitability of commercially available Bacillus probiotics on growth, survival and production of black tiger shrimp (Penaeus monodon Fab.) M.L. Islam*, S.K. Pal and M.J. Alam Brackishwater Station, Bangladesh Fisheries Research Institute Paikgacha, Khulna 9280, Bangladesh *Corresponding au thor Abstract Different forms of Bacillus probiotics was assessed in the earthen ponds on tiger shrimp (Penaeus monodon) culture. The experiment was designed with three different treatments depending on the mode of application (T1 = oral probiotics; T2= spreading probiotics and T3= oral+ spreading probioties). The shrimp was cultured for 120 days with the stocking density of 6-PL/m 2 • Oral probioties in the respective ponds were supplied with feeds. Whereas, spreading probiotics was applied to the pond water during pond preparation at 30, 60 and 90 days of culture period. Results of the experiment revealed that, all forms of Bacillus probiotic had effective role to keep the culture environment friendly in terms of mineralization of organic matter, nitrogen and phosphorus content in bottom sediment; holding of water transparency in a congenial state, increasing the density of planktonic biomass and boosting the THB- Vibrio ratio in water and scdimen t with insignificance (p>0.05) difference betvveen different treatments. Whilst, spreading form of Bacillus pro biotic showed higher weight gain (27.58 ± 1.18g), survival rate (70.75±8.54%) and production (1167.66±109.62 kg/ha) and expected lower FCR (1.81 ±0.06) values with significant difference (p<0.01) with others methods of application, indicated its superiority in tiger shrimp culture. Keywords: Probiotics, Penaeus monodon, shrimp culture Introduction Shrimp aquaculture particularly the culture of Penaeus monodon, has expanded rapidly throughout Asia in recent decades. Bangladesh has a trend of expanding culture areas as it has a high value of sea food products in the international market. One of the critical issues of shrimp culturists today involves the management of water and the volume of organic sludge being created within the pond during rearing periods and later being released into surrounding waterways. The use of probiotics in aquaculture is increasing with the demand for more environment friendly aquaculture practices (Gatesoupe 1999). A growing concern for the high consumption of antibiotics in aquaculture has initiated a search for alternative methods of disease control. In aquaculture, particularly