Zebrafish are the world's most widely used research fish, increasingly also used in conservation breeding - welfare understanding is advancing but implementation lags.
Zebrafish welfare has been transformed from a largely neglected concern to an active research area over the past decade. Regulatory protections apply to zebrafish under EU Directive 2010/63/EU and UK law. Key welfare improvements include social housing, optimised tank environments with appropriate flow and complexity, and refined handling protocols. The scale of zebrafish use - tens of millions annually - means even small per-fish welfare improvements translate into enormous aggregate benefit. Research into zebrafish welfare and refinement is a high-impact application of the 3Rs framework.