Zebrafish and other fish are used in millions of research procedures annually, with welfare standards that vary widely between institutions.
Research fish welfare occupies an unusual regulatory position — fish are protected by welfare legislation in some jurisdictions but not others, and even where protected, practical welfare implementation lags behind that for mammals. The scale of zebrafish research — millions of animals — combined with rapidly advancing sentience science creates a growing welfare imperative. Refinement approaches including environmental enrichment, appropriate stocking densities, refined husbandry protocols, and consistent analgesia for painful procedures can substantially reduce suffering without compromising research validity. Institutions that treat research fish welfare seriously report improved data consistency as an additional benefit of better welfare standards.