Abstract: Objective To observe the molluscicidal effect of chlorosalicylicamide on Oncomelania hupensis and toxicity on fishes. Methods Different concentrations of chlorosalicylicamide were prepared， and immersion and spraying methods were used to test its molluscicidal effect and toxicity to fishes. Niclosamide ethanolamine salt was used as control. Results Under water temperature of 28 ℃ with the dose of chlorosalicylicamide at 0.25 mg/L and 0.4 mg/L， the mortality rate of snails by immersion was 97.8% and 100% respectively after 48 h， and the LC₅₀ was 0.067 4 mg/L. While for niclosamide at the same doses， the mortality rate of snails was 22.2% and 66.7% respectively， and the LC₅₀ was 0.397 6 mg/L. With the concentration of 0.4 mg/L for 72 h， the fish death rate in chlorosalicylicamide and niclosamide was 50.0% and 100% respectively. Conclusion Chlorosalicylicamide shows a molluscicidal effect on Oncomelania snails and a lower toxicity to fishes than that of niclosamide.

Key words: Chlorosalicylicamide, Niclosamide, Oncomelania hupensis, Molluscicide