Fish Diseases and Management

5.1.1. Gram negative bacterial infections

There are different species of bacteria belonging to the genus Aeromonas, capable of causing disease in fish. The important species are Aeromonas salmonicida - aetiological agent of furunculosis in salmonids and A. hydrophila which mainly affect tropical fishes. They are non-sporing, facultatively anaerobic rods with rounded ends and resistant to the vibriostat compound ( 2,4 diamino 6,7 diisopropyl pteridine) . Optimum growth temperature is 22-28 ° C and some do not grow at 35 ° C. They occur widely in freshwater and sewage. Some are pathogenic to fish but rarely to man.