Bacterial prevalence in necrosis of freshwater shrimps (Macrobrachium rosembergii, Decapoda, Palaemonidae)

Abstract

The authors present bacterial agents occurrence in necrosis of cultured freshwater shrimps (Macrobrachium rosenbergii) in São Paulo State, Brazil. The shrimps showed black spot of various size on exoskeleton surface, on the carapace and abdomen, rostrum, uropods and periopods. In the bacterial cultivation it was isolated the genera Aeromonas, Pseudomonas and Vibrio, chitinolitic bacteria inhabitant of water and opportunist. Those bacteria utilize previous lesions of the exoskeleton as alimentary source determining necrosis, mutilation and death depending upon the commitment surface of the body. Besides these agents, it was isolated coagulase negative Staphylococcus sp., Escherichia coli and Proteus sp. Those lesions were determined by failures in alimentary and sanitary management in shrimp farms, as well as in the control of populacional density of pounds.