Acute fish toxicity testing is an important component of the environmental hazard assessment of chemicals. Since many years, (zebra-)fish embryo-based methods have been proposed as alternatives to the acute fish toxicity test carried out with juvenile or adult fish. On behalf of the Organisation for Economic Cooperation and Development (OECD), the European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM) coordinated during 2008-2012 the validation of the zebrafish embryo acute toxicity test method (ZFET) to evaluate its reproducibility in support to the development of an OECD Test Guideline. In parallel to this study, Belanger and colleagues continued to collect acute fish embryo toxicity and acute fish toxicity data to assess the relevance, predictive capacity and applicability of the ZFET and submitted their report to EURL ECVAM in July 2012. Following independent scientific peer review by EURL ECVAM's Scientific Advisory Committee (ESAC) of both studies and having considered input from regulators, stakeholders, international partners and the general public, EURL ECVAM concluded that the ZFET - being available as OECD TG236 since 2013 ? should be used for generating information on acute fish toxicity, where appropriate. Its use would result in an overall reduction of the numbers of juvenile and adult fish for aquatic toxicity testing. It is recognised that further guidance on the use of OECD TG236 across the various regulatory frameworks and regions should be developed addressing in particular the possible use of the ZFET to generate information on acute fish toxicity and its potential limitations.