Isolation and identification of pathogenic bacteria and fungi isolated from skin ulcers of Cirrhinus mrigala

Diseases like epizootic ulcerative syndrome (EUS), hemorrhagic septicemia, fin and tail rot, gill rot, dropsy etc. are caused in fish due to bacterial pathogens. The present investigation was carried out to isolate and characterize fish pathogens obtained from the diseased fish collected from different farms around Hisar, Haryana, India. Six types of pathogenic bacteria and a fungus were found to cause the epizootic ulcerative syndrome disease. A number of biochemical tests were carried out for identification of these causative agents. Six pathogenic bacteria viz. Streptococcus grp Q1, Aeromonas hydrophilla, Shigella spp., Streptococcus faecalis, Cellobiosococcus sciuri, Micrococcus luteus were identified. The fungus, Aphanomyces invadens was also identified and isolated from the diseased fish. Based on the programme PIBwin, ID scores were allotted to each bacterial isolate and matched/compared with the standard scores of the reference bacterium and on this basis the bacterial isolates were tentatively identified. The pathogenicity of disease causing organisms was confirmed through both in vitro and in vivo experiments.