Seasonal Fluctuations of Motile Aeromonads and Pseudomonads in a Cultured Pond of Mrigal, Cirrhinus mrigala, in Bangladesh

Abstract

Ecological studies on Aeromonas spp. and Pseudomonas spp. in mrigal, Cirrhinus mrigala, culture ponds were conducted in two fish farms in Bangladesh. The prevalence of Aeromonas spp. was high in pond water and in slime of the sampled fish in both fish farms during the winter season, when many diseases, including Epizootic Ulcerative Syndrome (EUS), occur. Pseudomonas spp. was also found in high percentages in the same sampling sites. High amounts of Aeromonas spp. and Pseudomonas spp. were also found in apparently healthy fish during winter. Frequent isolation of Aeromonas spp. from lesions of the sampled fish indicated a link between these bacteria and the out• break of fish diseases in the country. The detected Aeromonas spp. was resistant to various antibacterial agents tested. A high percentage of Aeromonas isolates were found to be resistant to erythromycin and oxytetracycline. However, only a few were resistant to oxolinic acid and streptomycin.