Md. Bazlur Rashid Chowdhury
Department of Aquaculture, Faculty of Fisheries, Bangladesh Agicultural University, Mymensingh, Mymensingh 2202, Bangladesh
Aeromonas, Pseudomonas, Antibiotic, Drug resistance, Pathogenicity, Carp, Catfish
Mymensingh and Gazipur (Dhaka)
Pest Management
Investigation of fish disease in Bangladesh An investigation on the outbreak of diseases in the farmed fishes of Bangladesh was carried out during 1991-1993. At first, in 1991 a survey was performed taking data and information from the fish farmers, farm managers, or the fishery officers of a particular locality or thana area. They provided the data from 1988 when the outbreak of EUS started in the country. In total 150 ponds under 40 fish farms throughout the country were taken for investigation. In 1992-1993 the data for the disease incidence was recorded by the graduate researchers by taking fish samples from the same locality, fish farms and ponds. Incidence of disease was categorized into the outbreak of typical EUS, the appearance of spots and various types of lesions other than EUS, tail and fin rot type disease, parasitic infection (ectoparasites) and the unknown diseases. The investigated farmed fish species were the carps (Labeo rohita, Catla catla, Cirrhinus mrigala, Puntius gonionotus, Hypophthalmicthys molitrix), and catfishes (Clarias batrachus, C. gariepinus, Clarias sp. hybrid, Pungasius sutchi). Sampling In total 30 fish ponds under 10 fish farms was selected to monitor the total bacterial load, aeromonads and pseudomonads contents in the water, sediments, fish body surface (slime) and kidney. The data were collected from 10 samplings scheduled once in a month. The selected farms were in the district of Mymensingh and Gazipur (Dhaka), viz., Dhaka Fisheries Ltd., Bangladesh Catfish Farm Ltd. Trishal fish farm, Mashkanda fish farm, BFRI fish farm, University fish farm, Faculty fish farm, Shambuganj fish farm, Jhalak fish farm and Gouripur government fish farm. Fish were sampled from the three ponds of each these farms. The regular sampled fish species were L. rohita, C. catla, C. mrigala, P. gonionotus and C. gariepinus. In total 120 fish were collected in the 10 samplings for each fish species. All the sampling sites were within 2 h driving distance from the Faculty of Fisheries, and the samples were brought to the laboratory immediately after collection for the bacteriological study. Determination and isolation of bacteria The total bacterial load in the water, sediments, and fish slime and kidney were determined on Trypton Soya Agar (TSA, Oxoid) by the conventional plate culture method. Aeromonads were determined on a selective medium Aeromonas-Agar Base (Oxoid) plate supplemented with ampicillin SR 136 E (commercial code) which was found to be a suitable medium for isolation and determination of aeromonads (Chowdhury and Inglis, 1994b). Pseudomonads were determined on another selective medium, Pseudomonas Agar Base (Oxoid) plate supplemented with antibiotic C-F-C (Cetrimide-Fucidin-Cephaloridine) SR 103 E (commercial code). This medium was previously proved to be a suitable medium for isolation and determination of pseudomonads from fish, water, or soil (Chowdhury and Inglis, 1994a). Tenfold dilutions of samples were made in sterile saline (0.85% NaCl) whenever necessary for all cases and the inoculated plates were incubated at 250C for 24 h-48 h. Aeromonad and pseudomonad isolates were carefully separated aseptically from the freshly cultured plates containing 50•`80 colonies depending on the colony shape, size, and colour. Special attention was drawn to recover the isolates from the kidney and lesions of the affected fish in order to isolate the suspected pathogens.
Fish Pathology,33(4),247-254,1998.10
Journal