As a series of studies on the suitability as a second intermediate host of Clonorchis sinensis, the wormicidal effects of mucus from epidermis of Cyprinus carpio nudus were observed. The results obtained were summarized as follows: On the silica gel thin layer chromatography with the greenish yellow supernatant in acetone:benzene/10:90 as carrier, seven spots were observed in iodine chamber. The spot of Rf. 0.225 value among them disclosed the strongest wormicidal effect on the cercaria, the excysted metacercaria, and the adult of C. sinensis. Meanwhile, no seasonal variations were found in Rf. values and effect of the wormicidal fractions. The wormicidal materials in epidermal mucus of C. carpio nudus and Carassius carassius were compared in their effect, and the former was more effective killing substance than the latter. It seemed that C. carpio nudus could not be proper intermediate host of C. sinensis according to results of the present study, in addition to our previous observation results.
