Anaesthesia is used daily in fish experimental procedures; however, the use of an inadequate anaesthetic protocol can compromise not only the animal's welfare but also the reliability of results. The use of zebrafish (Danio rerio) in biomedical research has increased in the last decades, highlighting the importance of appropriate anaesthetic regimens for this species. This article reviews the main anaesthetic agents and protocols used in laboratory adult zebrafish, and some of the analgesic methods to be used in this species that still need more research. In addition, a systematized observation of signs is proposed to evaluate adult zebrafish welfare to reduce pain and distress.The authors thank to Hugo Santos (BOGA, CIIMAR - Interdisciplinary Centre of Marine and
Environmental Research), Ana Cristina Borges, Maysa Franco e Liliana Vale (IGC - Instituto
Gulbenkian de Ciência), Petra Pintado e Fábio Valério (CEDOC - NOVA Medical School), and Sandra
Martins (Champalimaud Foundation) for the critical comments on the scoring sheet table. This work
was supported by the Post-Doctoral Fellowship SFRH/BPD/103006/2014 funded by FCT, and by the
Fellowship BI/CITAB/UTAD/VET/2015 supported by: European Investment Funds by
FEDER/COMPETE/POCI– Operacional Competitiveness and Internacionalization Programme, under
Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for
Science and Technology, under the project UID/AGR/04033/2013
