Objective and Methods As a local species, Chinese rare minnow (Gobiocypris rarus) has been one of the standardized test fish for chemical toxicity tests in China .By optimal screening , the acute toxicity of potassium bichromate and 3,4-dichloroaniline (3,4-DCA) was determined to evaluate repeatability and accuracy for Gobiocypris rarus in one laboratory and between different laboratories .Result Based on a proper data analysis , for the two chemicals per-formed with the same fish, all 96 h LC50 values were within mean ( x-) and upper and lower control limits ( ±2s) in both inner test ( in one laboratory ) and outer test ( between different laboratories ) .Conclusions From these results , a valid database could also be established to evaluate one single test .In addition, Gobiocypris rarus will not only be a potential test species for ecotoxicity tests , but also recommended as a standard laboratory animal .