Involvement of Aeromonads and Pseudomonads in Diseases of Farmed Fish in Bangladesh.

Abstract

Studies were conducted to investigate the bacterial infection in the farmed freshwater fishes of Bangladesh. Fishes in a number of farms were found to suffer from diseases expressing different kinds of skin lesions, tail and fin rot, gills damage etc. From the high numbers of aeromonads and pseudomonads in the lesions and kidney of the affected fish, these bacteria were suspected to be involved in those diseases in carp and catfish. The present study describes their occurrences in different aquaculture facilities including fishes, their resistance to various antibacterial agents, survival of some selected isolates in different waters and pathogenicity of the selected isolates. Both aeromonad and pseudomonad isolates were found to possess multiple patterns of resistance to the antibacterial agents tested. The selected isolates showed similar survival patterns in the experimental waters tested. Tap water, pond water and saline supported the long-term survival of both aeromonads and pseudomonads. Among the selected aeromonad isolates, Aeromonas hydrophilawas confirmed experimentally to cause an ulcer type of disease in the farmed catfish, Clarias gariepinus. In the case of pseudomonads, the isolate PMR-3 recovered from the kidney of a diseased carp (Puntius gonionotus) produced disease suceessfully inP. gonionotus.