Acute Toxicity of Three Aquatic Drugs to the Gymnodiptychus dybowskii

【Objective】 To study the acute toxicity of three aquatic drugs to the Gymnodiptyc husdybowskii,provide scientific data for the fry breeding and germplasm resource protection of Gymnodiptychus dybowskii. 【Method】 The acute toxicity of formaldehyde, salt and high polyiod- ine to Gymnodiptychus dybowski juveniles with body weight of（75.23±5.08）g, was studiedat water temperature of（12.2±0.2）℃, pH of（8.6±0.1） and dissolved oxygen of（8.4±0.3） mg/L in still water. 【Result】 The semi-lethal concentrations（LD50） of Gymnodiptychus dybowski juveniles in formaldehyde, salt and high polyiodine were 89.27, 13580.67 and 44.89 at 24 h, 69.21,13010.59 and 38.46 mg/L at 48 h,56.23, 12 824.48 and 34.74 mg/L at 72 h, 48.07 mg/L, 12621.56 mg/L and 32.42 mg/L at 96h, and the safe concentrations were 12.48 mg/L, 3 582.37 and 8.47 mg/L.The sensitivity of Gymnodiptychus dybowskii juveniles to the three drugs was high polyiodine>formaldehyde>salt, all of which were good drugs to prevent and treat the disease of Gymnodiptychus dybowskii juveniles. 【Conclusion】 According to the grading standard of ecotoxicological hazard,high polyiodineand formaldehyde are a medium toxic drug, while salt is a low toxicity drug. In the prevention and treatment of juvenile fish diseases, drug dose concentration and immersion time should be strictly controlled.