Fish are increasingly used in biomedical research, and improving their welfare requires applying the 3Rs framework and developing species-appropriate housing and experimental standards.
Laboratory fish welfare has historically received less attention than mammalian species, yet evidence strongly supports their capacity for pain and stress. Suboptimal housing conditions cause chronic stress that compromises both welfare and data quality. The 3Rs framework - Replace, Reduce, Refine - applies fully to fish research. Replacing fish with cell cultures or in silico models where scientifically valid, reducing numbers through better experimental design, and refining procedures to minimise pain and distress should all be actively pursued.