CLINICOPATHOLOGICAL FEATURES OF ARBORESCENT ORGAN NECROSIS SYNDROME IN Clarias gariepinus (Burchell 1822)

摘要

Some teleosts such as the African catfish (Clarias gariepinus) posess accessory respiratory organs (arborescent organ) which enable them to breathe atmospheric air in hypoxic conditions. Arborescent organ necrosis syndrome is a relatively new diseasecondition of farmed African catfish in Nigeria .There is only one report of this syndrome in the African catfish, although several anecdotes of its occurrence exists. Six freshly dead catfishes were collected from two farms during a disease outbreak where severe high mortalities were recorded. At necropsy there was severe necrosis of the arborescent organ. Other gross lesions observed included severe gill hyperaemia and severe depigmentation of the skin. Histopathology revealed severe necrosis and nonsuppurative inflammation of the arborescent organ and gills, hepatocellular vacuolar degeneration and severe necrosis of the haematopoietic and non haematopoietic elements of the trunk kidney. Three organisms namely Aeromonas hydrophila, Pseudomonas putidaand Salmonella subsp IIIB were isolated from the necrotic arborescent organs and the dorsal and trunk kidneys. All the isolates were susceptible to ciprofloxacin. No mortalities were recorded on affected farms a day following the administration of ciprofloxacin to affected catfishes. Although this is not the first report of this syndrome in the African catfish, it is notable that thfc. organisms isolated in this case differ from what was isolated (Enterobacter cloacae and Aeromonas sobria) ifi the previously reported case.