Anthelmintic treatment against Gyrodactylus sp. infecting rainbow trout Oncorhynchus mykiss

Abstract

Various anthelmintics belonging to different pharmacological groups (ivermectin, clorsulon, closantel, netobimin, febantel, praziquantel, niclofolan, bithionol, trichlorfon, levamisole hydrochloride, piperazine citrate and dihydrochloride, nitroscanate), all of proven efficacy against certain helminths, were tested and compared for their in vivo and in vitro activity on a natural infection of Oncorhynchus mykiss by Gyrodactylus, probably G. salaris. The trout were also observed for signs of toxic reaction to the drugs. Complete efficacy (100 % reduction) with no toxic effects was achieved only by bithionol (20 mg l-1) and nitroscanate (0.07 mg l-1).