Abstract
Kamala, Bithionol, Nicrosamide and Parbendazole were tried to use for the prevention of spreading of Bothriocephalus opsariichthydis YAMAGUTI, 1934. Every anthelmintics were administered to tens or hundreds of thousands of four-month-old carp, each of which was kept in five ponds in Nagano prefecture, on October in 1975. Fifty eight fish collected randomly from each pond were examined at 5 to 7 days after administration.
The rate of fish which harboured the cestode was markedly reduced with these anthelmintics, but the average number of worms remained in the host did not decrease. This result means that all of fish kept in a vast pond never equally took a diet containing drugs. Beside it is difficult for us to certify that all of fish administered were parasite-free, even if no fish harboured any worms was detected on the only abstracted sample. We conclude from above mentioned reasons that using of anthelmintics to the young carp before their first wintering is scarcely any significance for the prevention against this cestode.
