Skin fluke infection of cultured marine fish

Abstract

Capsalid monogeneans infect the skin of marine fish; among them, Benedenia seriolae and Neobenedenia girellae are most important pathogens of cultured fish. The former infects the skin of amberjacks, Seriola spp., while the latter, being not host specific, has been found from the skin of 15 fishes in Japan. Feeding epithelial cells and mucous of the host results in skin abrasion, causing growth retardation and secondary bacterial infection, even leading to the death of the host fish. Eggs entangle on the culture net, which is prone to heavy infection of fish cultured in net cages. Prevention of infection is practically impossible as its life cycle has been established in fish farms. Chemotherapy with hydrogen peroxide or praziquantel is effective but repeated treatment is required, as immunity is not acquired by infected fish. Development of new control measures such as biological control and selective breeding of a resistant strain against these monogeneans are in progress.