Parasites of Freshwater Fishes in Cheju-do

Parasites of freshwater fishes in Cheju-do were studied from May 1989 to April 1990, and incidence of infection in 16 fish species was reported. Protozoan parasites (Trichodina sp., Chilodonella sp., Ichthyophthirius sp., Vorticella sp., Myxidium sp., Myxobolus sp., Henneguya sp:, Ichthyobodo sp., and Trychophrya sp.), water mold (Saproregnia sp.), two monogenes (Dactylogyrus sp. and Gyrodactylogyrus sp.), Trematods, Cestods, Nematods, Acanthocephalas, parasitic copepods(Lernaea sp. and Pseudergasilus sp.) and a Hirudinea were recognized as freshwater fish parasites in Cheju-do. Trichodina sp. showed the highest infection rate (18.3%). Fifty seven individual fishes out of 311 were infected by this parasite. Nematods showed the second highest infection rate (13.5%). Dactylogyrus sp., Acanthocephalas, and Trematods showed the third (4.8%), fourth (4.2%), and fifth (2.6%) infection rate respectively. Of the 16 fish species Cryptocentrus filifer (Gobiidae) showed the highest infection rate. Nineteen fish out of 28 have Trichodina sp., and 14 fish out of 28 have Nematods. Those infection rates were 67.9% and 50.0% respectively. No parasites were collected from the fishes of Gwangryung vally, Dosoon-chun, Gangjeong-chun, and Hyodon-chun.