Penaeus monodon was cultured during September-December, 2009 in the Kar shrimp farm at Keshabpur, Haldia (West Bengal), India (Lat 21º55' N, Long 88º46' E). Six rectangular earthen ponds (~ 0.5 ha) with both inlet and outlet facilities, were used in the experiment. Three ponds were randomly selected for probiotics treated series with another three ponds used for the control series (without probiotics). The source of water for all the experimental ponds was from the creek of the Haldi River. Water depth of the ponds was maintained between 110 cm and 120 cm throughout the culture period. Twenty-day old post larvae (PL20) of P. monodon (PCR tested negative for white spot syndrome virus, and are healthy) were procured from a reputed shrimp hatchery and stocked with 20 pcs.m-2 in experimental ponds after acclimatisation by keeping the polythene bags containing the PLs afloat in the pond water for one h and for an added ½ h after an equal volume of pond water was added into the polythene bags. Water exchange (0-10%) was performed once weekly and there was no exchange during the first 20 days, although water was added to maintain losses due to seepage and evaporation. Aeration was maintained for 4-8 h.day-1. The feed ration was divided into portions and fed over 2-4 times a day and the quantity was reduced or increased as per regular check tray observations (Clifford 1992). Shrimp were harvested after a grow-out period of 105 days. Both the treatment and control ponds were prepared and managed following the method described by Hasan et al. (2011).