Bacteriological Studies on Fishes Affected with Epizootic Ulcerative Syndrome

Abstract

Epizootic ulcerative syndrome is one of the most well known fish diseases that has caused disastrous effects throughout India after its first outbreak in 1988. Since then recurrences in varying intensities are reported every year. Bacteriological examination of the ulcerated area of affected C. punctatus, Puntius sp. and Mystus sp. revealed the presence of 16 strains of bacteria belonging to the genus Pseudomonas, Aeromonas, Micrococcus, Bacillus, Vibrio and Moraxella among which Pseudomonas and Aeromonas were the most common. Pathogenicity tests with all the isolates showed that only six strains belonging to the genus Aeromonas and Pseudomonas were pathogenic while the rest were nonpathogenic. The distinct inconsistency in the type of pathogenic bacteria isolated from the three fish species suggests that these are opportunistic pathogens that have invaded the fish secondarily.