The European Chemicals Agency (ECHA) has published advice on how to use the fish embryo acute toxicity (FET) test (OECD test guideline 236) under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation in Europe. The advice describes ECHA’s view on the scope and limitations of the FET test and indicates that it might be used in accordance with a weight of evidence approach to meet the information requirement for the short-term toxicity test on fish (REACH Annex VIII, 9.1.3) instead of using adult fish.