The Study on the Experimental Ascite by Edwardsiella tarda in Snakehead (Channa argus)

Edwardsiella tarda에 의해 유발된 가물치 복수증에 관한 연구

The bacterium Edwardsiella tarda was injected into healthy snakeheads (Channa argus) in order to prove the causative agent of ascite. The bacterium dominantly isolated from 2 cultured ascite snakeheads was injected into fish by the dose of $5\times10^6$ CFU/ 0.25ml, but the same dose of $0.65\%$ physiological saline was injected into the each control. The injected fish was divided into 4 groups such as intraperitoneal, intramuscle, control intra-peritoneal and control intramuscle according to their injection points. Each was composed of 10 healthy snakeheads respectively. Ascites and haemorrhagic ulcers became distinct 5 days after injection, but controls did not show any abnormal symptoms during the experimental period. Edwardsiella tarda was reisalated out of the injected fish's ascite, liver, kidney, spleen and haemorrhagic ulcer on the skin. Regardless of the injecting methods, liver was necrotized more severely than any other internal organ, but both the glomeruli of kidney and spleen were considerably damaged. Necrosis of muscle and a number of leucocytes were observed at the ulcerous region of the intramuscular injected fish. It is concluded that judging from the above results the Edwardsiella tarda is a causative agent to cause ascite in snakehead.