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 performed 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.