Isolation of some gram-negative bacterial species from naturally infected silver European eel fish (Anguilla anguilla linnaeus, 1758)

The aim of this study is to inform isolations of Shewanella putrefaciens, Aeromonas sobria and A. veronii from the silver European eel fish (Anguilla anguilla) caught from the Gulf of Antalya, Turkey. Three silver eel fish samples as freshly dead (mean weight 75 g) were obtained by a local fisherman. For bacteriological study, inoculations from the head kidney, spleen and liver were made and inoculated onto Brain Hearth Infusion Agar (BHIA-S) supplemented with 1.5 % NaCl. The inoculated petri dishes were incubated at 24 ± 2°C for 72 hours. The end of the incubation period, bacterial colonies were subcultured. For presumptive identification of the bacterial strains, the strains were identified using a variety of phenotypic characteristics. The further identification of the strains was performed with PCR. Clinically, the silver eel samples showed pale gills, losses of scale, necrotic lesions on dorsal, hemorrhagies on the jaws, lateral and ventral sides of the body and around the anus and hemoragic anal fin. At necropsy, the fish had enlarged and pale spleen and the gastrointestinal tract was empty. After 72 hours, 10 bacterial strains were isolated. 6 strains as Shewanella putrefaciens, 2 strains as Aeromonas sobria and 2 strains as A. veronii were identified according to the phenotypical characteristics and PCR study results. The eel fish stocks in natural conditions are decreasing and this problem may be multifactorial such as disease, migration and overhunting. As a result of this study, A. veronii was first isolated from A. anguilla.