Acute toxicity of copper sulfate and fenvalerate to zebrafish (Brachydanio rerio)

The present paper is aimed to report our experiments and investigations on the toxicity of the heavy melals and pesticides to zebrafish (Brachydanio rerio) by using standardized laboratory procedures, along with our measurements on the acute toxicity of copper sulfate and fenvalerate.In proceeding with our experiments,we have tested and measure the sensitivities of zebarfish to these pesticides re- spectively by using medium lethal concentrations (LC_(50)) every 24 h, 48 h,72 h and 96 h.The results showed that the values of 24 h LC_(50),48 h LC_(50),72 h LC_(50)and 96 h LC_(50) of CuSO_4 were 12 mg/L, 7.9 mg/L,6.8 mg/L and 5.4 mg/L,respectively.The values of LC_(50) for fenvalerate were 1.2 ×10~(-4) mg/L,0.9× 10~(-4) mg/L,0.9 × 10~(-4) mg/L and 0.9×10~(-4) mg/L,respectively.The safe concentrations of the two pesticides were 1.03 mg/L and 1.52×10~(-5) mg/L,respectively.Though we have found that the copper sulfate is likely to lead to shape distortion of zebrafish,causing the phenomena of upside-down and the head-up,the scoliosis was not obvious.However, the fenvalerate can cause the bending of back and side in fish, which is of different characteristics.However,the pesticide fenvalerate proves more sensitive to zebarfish than the copper sulfate.There was no change in the death rate of zebarfish after 48 hours.According to the state requirements for toxicity-evaluating and grading of chemicals toxics to fish in China (GB/T 21281—2007),the toxicity of the two chemicals to zebarfish should be put at grade Ⅱand Ⅰ,respectively. The results show that the toxicity of the copper sulfate to the fish should belong to the moderate level with the 1.096 h LC_(50)≤ 10.0 mg/L,whereas the toxic level of fenvalerate with the 96 h LC_(50) ≤0.1 mg/L belongs to high-toxic material to zebrafish.Hence,this study can be said to have provided the theoretical basis for the rational application of copper sulfate or fenvalerate,when they are used in aquaculture in prevention and control of fish diseases.