Zebrafish are social animals whose welfare is improved by group housing. Research institutions are increasingly recognizing social housing as a welfare standard for this species.
Zebrafish welfare has historically been treated as a minor consideration relative to the research outputs they enable. Growing evidence that zebrafish are social animals whose wellbeing is impaired by isolation has changed the standard of care expected in responsible research facilities. Group-housed zebrafish show lower stress indicators, better immune function, and more typical behavioral profiles than isolated individuals. These welfare improvements also benefit research quality: stressed animals with dysregulated physiology introduce confounding variables into experimental results. Social housing serves both welfare and scientific integrity.