Ulcer Type of Disease in the Fishes of Small-Scale Farmer’s Pond in Bangladesh

Abstract

Studies were conducted to investigate ulcer type of disease in the small-scale rural poor fish farmer's pond and to suggest a low-cost treatment measure. In total 20 ponds of 10 different sites were selected in Mymensingh district considering as treatment and control ponds. Fishes were sampled on monthly basis starting from September 2000 and continued until April 2001 to examine their disease condition. The disease was detected by observation of lesions on the fish body surface and subsequently by laboratory examination. A number of suspective bacterial pathogens were recovered form the lesions and kidney of the diseased fishes, Cirrhinus mrigala, Labeo rohita, Catla catla, Barbodes gonionotus, and Pangasius sutchi. Fungal isolates, especially Aphanomyces sp. and Saprolegnia sp. were recovered form the lesions and affected muscles of the sampled fishes. Among the bacterial isolates, Aeromonas sp. Pseudomonas sp. and Edwardsiella sp. were found to be pathogenic. In the case of fungal isolates both Aphanomyces sp. and Saprolegnia sp. were detected as pathogenic. Low-cost preventive treatments were applied in the selected farmer's ponds on the basis of preliminary studies under laboratory condition. Disease outbreaks were found to be very low where preventive treatment measures were taken using the pre-selected successive doses of salt and lime (1:1, 1kg/decimal). In the winter months (December to February), the disease outbreaks were found to be very high in the control ponds (non-treated), whereas in the treated ponds infection were significantly low. In laboratory based treatment trial, antibiotic renamycin was found to be effective against bacterial invasion at a dose of 50mg/kg body-wt/day applying for five days. For fungal infection the diseased fishes were found to be cured within five days by one hour bath in 0.5% salt and lime suspension at a ratio of 1:1 applying for 3 days.