2007 Volume 42 Issue 1 Pages 35-39
The causative agent of kuchijirosho (snout ulcer disease), an infectious disease of tiger puffer Takifugu rubripes, is filterable, detailed characteristics of the agent have not been clear. Here, susceptibility of eight fish species against kuchijirosho was studied by injection with the kuchijirosho agent. A hundred percent mortality with typical signs of kuchijirosho was observed in tiger puffer, grass puffer T. niphobles, panther puffer T. pardalis and blue-spotted boxfish Ostracion immaculatus, while no mortality occurred in Japanese parrotfish Oplegnathus fasciatus, largescale blackfish Girella punctata and red seabream Pagrus major. Moreover, yellowtail Seriola quinqueradiata was demonstrated to be susceptible to this disease, because cumulative mortalities of 100% and 60% were recorded in young (average 12 g in body weight) and adult (average 530 g in body weight) yellowtail, respectively. Affected young yellowtail exhibited convulsion with the curvature of the spine (scoliosis), although no typical disease sign was observed in the dead adult yellowtail. In experimental infection with the brain homogenate of the dead adult yellowtail, scoliosis was produced in young yellowtail.
