Zebrafish have become one of the most widely used vertebrate research models — but their welfare has historically received far less attention than mammalian research species.
Zebrafish occupy an awkward position in animal research welfare — their small size, fecundity, and genetic tractability make them enormously valuable research tools, while their welfare has been systematically undervalued compared to mammalian models. The assumption that fish feel less than mammals has been repeatedly challenged by behavioral and neurological research. Zebrafish show robust stress responses, learn to avoid aversive stimuli, and demonstrate individual behavioral differences that suggest genuine individuality. Improving zebrafish research welfare requires applying the same principles of refinement, reduction, and replacement that govern mammalian research — with appropriately species-specific approaches to housing, enrichment, and analgesia.