Diagnosis of Aeromonas sobria and Saprolegnia sp. co-infection in rainbow trout fry (Oncorhynchus mykiss)

The aim of the study was to determine a considerable level mortalities occurred in rainbow trout fry (Oncorhynchus mykiss) cultured research hatchery located Marmara Region/Turkey. Totally 18 individuals (1-8 g) were investigated by using bacteriological and mycological methods. affected fish showed skin darkening, prolapses fungal mats at base fins. According morphological biochemical characteristics isolates, all them identified as Aeromonas sobria. Saprolegnia sp. also observed squash preparations skin. All isolates determined be sensitive against florfenicol, enrofloxacin ciprofloxacin. Histopathologically, vacuolar degeneration, haemorrhage hyperaemia liver, tubular necrosis, periglomerular edema, multifocal melanomacrophage deposits kidney depletion white pulp spleen determined. Distal type epithelial cells hyperplasia gills. In diseased fish, motile Aeromonad septicaemia described detected fins lesions but it considered secondary infection.