Zebrafish are the second most commonly used vertebrate research species with welfare needs including social housing, environmental complexity, and species-appropriate water conditions that are increasingly recognized.
Zebrafish welfare has historically received less attention than mammalian research species despite their vertebrate status and growing evidence of sentience. Standard laboratory housing often fails to meet their social and environmental needs. Social isolation causes measurable behavioral and physiological stress. Barren environments deny the exploratory and shoaling behaviors that are natural to the species. As zebrafish use in research continues to grow due to their genetic tractability, ensuring welfare standards keep pace with their increasing use is an important scientific and ethical obligation. The 3Rs framework requires refinement of zebrafish housing and handling as welfare science develops.