Clarias batrachus (Linn) is a species of catfish of the family claridae. A survey was carried out for a period of one year from May 2008 to June 2009 to study the prevalence of bacterial ulcerative disease in C. batrachus, reared in a farm located at Walajapet, Vellore Dist., Tamil Nadu, India. To reproduce the infection in healthy catfish, organs such as liver, spleen and tissue were used to prepare the inoculum in NTE buffer. The inoculum was injected into healthy fingerlings through intramuscular injection and immersion challenge. The tissue supernatant from infected catfish was screened for isolation and identification of the causative organism responsible for ulcerative syndrome in catfish. Based on biological, biochemical, morphological and physiological characters the isolate isolated from infected catfish was tentatively identified as Aeromonas caviae-like bacterium. It was further confirmed by the analysis of 16S rRNA gene of A. caviae using PCR. © 2012 Elsevier B.V.