The population size, generic diversity and potential to produce hydrolytic enzymes of heterotrophic bacteria associated with pond reared Penaeus indicus was worked out following standard bacteriological procedures. Chitinoclastic vibrios were found to be the major flora associated with juveniles of P. indicus in the culture environment when they were maintained in hapa. Bacterial flora of the body surface and gills of the prawns in a grow out system were predominantly composed of Pseudomonas, Coryneform group, Vibrio and Pseudomonas as the major genera, much different from that of pond sediment from where the animals collected detritus, indicating the animals' selective feeding behaviour. Intestine of prawns was found to be a congenial environment for the chitinoclastic vibrios to undergo a few cycles of division, suggesting their profound role in the digestion of chitin. The possible dual role which Vibrio might play in a grow out system of P. indicus is described.