A. KRISHNIKA AND P. RAMASAMY
Abstract
Bacterial diseases are responsible for the high mortality and severe economic loss to the prawn aquaculture industry development especially in the culture giant fresh water prawn M. rosenbergii. The present study was initiated to assess the occurrence and distribution of presumptive Vibrios and suggest control measures in hatcheries of fresh water prawn M. rosenbergii in tropical South India. The present study has shown the occurrence of a very high load of total heterotrophic bacterial count and total presumptive Vibrio count in the eleven different larval stages of M. rosenbergii. Total heterotrophic bacterial count was higher in the larval tank water throughout the cycle of the M. rosenbergii larval culture. Treatment methods chlorination, application of antibiotics, UV radiation alone and a combination of sequential treatments starting from chlorination (2ppm) followed by sand filtration, dechlorination, UV radiation (10 sec) and microfiltration (5μm size) were carried out and the study has also shown that the sequential treatments in M. rosenbergii had resulted in the gradual reduction of bacterial counts and these are shown to be the best methods to control the bacterial population in hatcheries of fresh water prawn M. rosenbergii.