Mortality of Wild Three-lips Opsariichthys uncirostris by Infection with Chilodonella　hexasticha

Abstract

Mortalities of three-lips Opsariichthys uncirostris occurred in a river in Shiga Prefecture, Japan, during the summer of 2013. The gills of diseased fish were heavily infected with the parasitic ciliate Chilodonella hexasticha. The intensity of parasite was 0.73-1.15 millions in dead fish, and 0.45-0.52 millions in apparently healthy fish. The cause of fish death may be a respiratory dysfunction by congestion due to the heavy infection with C. hexasticha on the gills. This is the first report of C. hexasticha infection of wild fish in Japan.