• Journal of fish pathology
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• v.10 no.2
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• pp.113-123
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• 1997

Concerned to the life cycle of Ichthyophthirius multifiliis, the biological characteristic of the parasites was studied in the rainbow trout (Oncorhynchus mykiss) and the Korean catfish (Silurus asotus) Under the experimental condition of $9^{\circ}C$- $28^{\circ}C$, tomitogenesis rate was positively proportional to water temperature, but not at over $28^{\circ}C$. The protomonts showed a high rate of tomitogenesis at $26^{\circ}C$ in comparision with other temperature conditions. Temperature affected tomitogenesis rate which resulted from the various conditions of salinity, pH and formalin concentration. The protomonts showed a high rate of tomitogenesis at pH 6.9 in comparision with other pH conditions at all temperatures tested. This result revealed that the opitimum pH for tomitogenesis was 6.9. The protomont had more tolerance against salinity and formalin concentration at low temperature ($18^{\circ}C$) than at high one ($22^{\circ}C$). Both trophont and protomont were not infective, but theront was infective.