Zebrafish have become among the most widely used vertebrates in biomedical research. As their use expands, understanding their welfare needs and developing species-appropriate standards becomes increasingly important.
Zebrafish welfare presents emerging challenges as their use in research grows rapidly. The regulatory gap around embryonic stages means welfare protection begins later than the evidence on nervous system development suggests is appropriate. Adult zebrafish in research facilities require group housing, appropriate environmental complexity, and carefully maintained water quality for welfare-positive conditions. High-density housing for efficiency conflicts with space requirements for normal social behaviour. Handling and sampling procedures cause measurable stress responses. The development of welfare indicators, environmental enrichment approaches, and humane endpoint definitions appropriate for zebrafish is an active and important field. Better zebrafish welfare standards also improve research reproducibility by reducing stress-induced variability.