Zebrafish are social animals whose welfare in research settings depends on appropriate group housing rather than isolation protocols common in some facilities.
Zebrafish social housing welfare reflects the broader principle that laboratory animal welfare improves scientific quality rather than compromising it. Isolated zebrafish are chronically stressed animals that show altered baseline physiology and behavior, confounding experimental results. Group housing produces calmer, more consistent behavioral baselines while meeting social welfare needs. The 3Rs framework — Replace, Reduce, Refine — requires applying refinements that improve welfare, and for zebrafish this includes social housing as a standard expectation. Institutional protocols that default to isolated housing should be updated to reflect current welfare science.