Zebrafish are among the most widely used vertebrates in biomedical research. Their welfare needs have historically received less attention than mammalian species but are increasingly recognised.
Zebrafish welfare has historically fallen through the gap between mammal-focused welfare frameworks and invertebrate research. As vertebrates with demonstrated capacity for pain and stress, they deserve welfare protections equivalent to other research species. Their small size and aquatic nature have led to housing conditions that would be unacceptable for mammals - individual isolation, barren tanks, and limited environmental complexity. Applying the same evidence-based enrichment principles that have improved mouse welfare to zebrafish research represents an achievable and necessary welfare advance.