This study was carried out to determine the aethiological agent of an infectious fish disease that induced high mortality in a guppy production unite.
Affected fish (2-4 g in weight) showed pale gills, darkening of the skin, fin rot, aimless swimming, loss of uqilibrium, convulsions, paralysis, and death. Internally pale liver and kidney, enlarged cherry red spleen and swollen bile duct were noticed. Bacteriological inoculations were made from the infected fish kidney, liver and spleen to Trypiic Soy Agar (TSA) and Anacker and Ordal Agar (AOA). The isolated bacteria were identified according to cellular morphological, physical, and biochemical characteristics. From this epizootic. 4 isolates were identified as Flavobaclerium spp. and 2 isolates as Pseudomonas fluorescens, were recovered. Oxytetracycline was found most sensitive to both bacteria isolate. Sick fish treated with this antibiotic in food was found effective with seven days application.