The fish extoparasite Ichthyophthirius multifiliis was subjected to tricaine methanesulfonate (TM) exposure while fish were anesthetized for parasite collection. No information is available on the effects of TM exposure to I. multifiliis. This study evaluated the effects of TM on the survival and reproduction of I. multifiliis. Significant differences were not observed in survival and reproduction of tomonts collected from fish anesthetized using unbuffered or buffered TM or in control fish not exposed to TM. Results of the current study demonstrated that TM had no adverse effect on I. multifiliis survival and reproduction when used at concentrations and exposure times required for fish anesthetization.