Zebrafish and other fish species used in biomedical research present specific welfare challenges, and the 3Rs framework is driving improvements in fish welfare and alternatives development.
Laboratory fish welfare has received increasing attention as evidence of fish sentience has strengthened. The scale of zebrafish use in research means that even modest per-animal welfare improvements aggregate to substantial total suffering reductions across the research population. Anesthesia for painful procedures, previously inconsistently applied due to uncertainty about fish pain experience, is now more widely used following updated guidance from regulatory bodies. Refinement of housing conditions to include appropriate social grouping, flow rates, and environmental complexity improves baseline welfare for the duration of fish lives in research facilities. Replacement with non-sentient alternatives is advancing but will not eliminate fish use for complex biological questions requiring intact organism responses.