As zebrafish use in research grows, developing appropriate group housing standards is critical for their welfare in laboratory settings.
Zebrafish welfare in research settings is often managed at a basic level - adequate water quality and feeding - without addressing the social and behavioral complexity that characterizes their natural life. Isolated zebrafish show anxiety-like behavior, altered cortisol, and different pain responses compared to socially housed fish. The relative ease of maintaining zebrafish has sometimes been used to justify lower welfare standards than applied to mammalian research models. As evidence for zebrafish sentience and pain responsiveness grows, the ethical obligation to apply 3Rs principles rigorously to zebrafish research becomes more compelling.