EUS infected fishes and isolated bacteria from them in eastern Nepal
Ganesh Bahadur Thapa, Joydeb Pal
Present study deals with isolation, characterization and identification of bacteria from EUS infected fishes and pathogenicity of isolated bacteria from EUS affected fishes from eastern Nepal. Out of six water bodies EUS outbreaks were recorded in three fish farms S1, S2 and S3 from 2009-2015. Generally the outbreak of EUS takes place in the month of December and persists up to March. Altogether 444 naturally EUS affected fishes were collected and examined. The order of susceptibility was about 60% Cirrhinus mrigala, 30% Labeo bata / L. rohita, 7% Catla catla, 3% Channa striatus, Puntius sp., Heteropneustes fossilis,Mystus tengara, Clarias batrachus and Lepidocephalichthys guntea (rarely) among affected fishes. Bacteria were isolated from the ulcers of naturally infected Cirrhinus mrigala, Catla catla, Channa striatus, Puntius sp., Mystus tengara and Labeo bata. Among 23 isolates, 2 belong to Pseudomonas sp. from Lb1 and Cc4, 2 belong to Micrococcus sp. from Cm2 and P4, 14 bacteria were of Aeromonas hydrophila isolated from Cm1, Cm3, Cs1, P1, P3, Lb2, Lb3, Cc1, Cc2, Cc3, Mt1, Mt2, Mt3 and Mt4. 1 belongs to Moraxella sp. from P2, 1 belongs to Aeromonas veronii biovar sobria from Lb4 and 3 belong to Aeromonas caviae from Cm4, Cs2 and Cs3. All together 20 bacterial isolates were pathogenic and 3 were non- pathogenic. EUS (Epizootic Ulcerative Syndrome) is the major microbial fish disease in eastern Nepal.