In the last decade the number of publications in zebrafish tripled, from 938 in 2005 to 2432 in 2015 (Pubmed database; keyword: “zebrafish” in Title/Abstract; 12/4/2015), being the animal model with the highest increase in publication. These numbers reflect the importance of zebrafish as a good practical and scientific model for several human diseases, drug discovery and gene function identification through behavioural phenomics and high-throughput genetic and molecular screening.

     Zebrafish is legally protected by the European Directive on the protection of animals used for scientific purposes (2010/63/EU) when they become capable of independent feeding.
     
     However, the increasing use of zebrafish has not been accompanied by the evolution of anaesthetic protocols suitable for different experimental situations. Ethyl 3-aminobenzoate methanesulfate (MS222) is the standard fish anaesthetic, but concerns have been raised concerning aversion/ stress induction and cardiovascular depression in long procedures. This lecture intends to provide a review of the anaesthetics used in zebrafish in different contexts and the proposal of new anaesthetic protocols. The drugs’ availability, preparation, clinical efficacy and safety, and animal welfare issues will be discussed.

     There are legal, scientific and animal welfare reasons to study procedures’ refinement in zebrafish. This animal model needs proper research in the area of laboratory animal science for a better care and scientific quality.