Removal and Quantification of Asian Tapeworm from Bonytail Chub Using Praziquantel

Abstract

The spread of the Asian tapeworm Bothriocephalus acheilognathi has been identified as a potential threat to endangered cyprinid fishes, such as bonytail Gila elegans and humpback chub G. cypha. Praziquantel is often used to remove Asian tapeworms from these species, but little information is available on the effectiveness or side effects of these treatments. I performed laboratory experiments using bonytails (110–457 mm total length) to evaluate the dosage and time needed to effectively remove 100% of Asian tapeworms using praziquantel. A low dose of 0.7 mg/L for 24 h was not effective at removing all Asian tapeworms, whereas a 24-h exposure at 1.5 mg/L and higher was 100% effective. A bath treatment of 12-h duration only appears effective at the highest dose of 36 mg/L, but not all Asian tapeworms are cleared from the host within this time frame. No short-term mortality or side effects of praziquantel treatment were observed. Praziquantel bath treatments can effectively and safely remove 100% of Asian tapeworms from bonytail if dosage and treatment duration are adequate. In some cases, repeated treatments may be necessary to ensure that Asian tapeworms are not spread into new environments.