Zebrafish are the second most widely used laboratory vertebrate and their welfare is increasingly recognised as important - improvements in housing, husbandry and experimental design benefit animal welfare and research quality.
Zebrafish welfare science has advanced significantly, demonstrating that conventional laboratory housing frequently fails to meet their needs. Zebrafish are social, active fish that require group housing, environmental complexity and appropriate water quality. Welfare refinements including enriched housing, optimised group sizes and stress-reduction protocols improve both animal wellbeing and research reproducibility - demonstrating that welfare and scientific quality are aligned rather than opposed. Regulatory frameworks for zebrafish welfare vary internationally, with the EU directive requiring welfare consideration but leaving implementation to institutions. Stronger, standardised welfare requirements would benefit both fish and science.