21-day Fish Assay (OECD TG 230)
The 21-day Fish Assay according to OECD TG 230 is a short-term chronic test designed to evaluate the effects of substances on fish, with a particular focus on endocrine-related responses. The test provides important information on sublethal effects that may impact fish physiology and reproduction.
In this study, sexually mature fish are exposed to a range of concentrations of the test substance under controlled laboratory conditions for a period of 21 days. During exposure, fish are monitored for general health and behavior, and specific biological endpoints are assessed at the end of the test.
Key endpoints include the measurement of vitellogenin levels (a biomarker for estrogenic activity), as well as gonadal histopathology and secondary sexual characteristics, depending on the species used. These parameters allow the identification of endocrine-disrupting properties and support the evaluation of potential mechanisms of action.
The test is not intended to provide full life-cycle data but serves as a screening and investigative tool for detecting endocrine activity in fish, contributing to environmental risk assessment and regulatory decision-making.
