Effect of age on the susceptibility of marbled rockfish, Sebastiscus marmoratus to Ochroconis humicola following experimental challenge

Abstract

SHORT COMMUNICATION

Infection by the fungus Ochroconis humicola causes mortality in juveniles of marine fish species including the marbled rockfish, Sebastiscus marmoratus, which is cultured in Japan (Munchan et al., 2006; Wada, Hanjavanit, Kurata, & Hatai, 2005; Wada, Nakamura, & Hatai, 1995). Erosive or ulcerative features on the body surface, especially skin lesions on the head, have been reported as the major clinical signs of O. humicola infection in Japanese marine cultured fish (Wada et al., 2005, 1995). These case reports suggest that O. humicola consistently infects younger fish. For example, Wada et al. (2005) recorded infections in juvenile marbled rockfish weighing about 1 g. However, there have not yet been any studies investigating the occurrence of O. humicola infection in relation to fish age. Therefore, our objective was to examine the association between susceptibility to infection and age of marbled rockfish.