GB/T 13267-1991 is a standard in the field of water quality, which aims to determine the acute toxicity of substances to freshwater fish (zebrafish). Zebrafish are sensitive to changes in water quality and are organisms that evaluate the toxicity of water bodies. The standard specifies in detail the preparation of the domestication of zebrafish before the experiment, the configuration of the tested substances, etc., elaborates the specific operation process of exposing zebrafish to different concentrations of test substance solutions, and judges the toxicity of substances by observing indicators such as the death of zebrafish within a specified time. It provides a scientific basis for monitoring water pollution and evaluating the hazards of chemicals to aquatic organisms, and helps to protect aquatic ecosystems.