The 3Rs framework (Replace, Reduce, Refine) for laboratory animal welfare must be adapted for the diverse species used in research, from zebrafish to pigs to non-human primates.
The 3Rs framework has transformed laboratory animal welfare since its introduction, but its application remains uneven across species. Refinements developed for mice and rats may be wholly inappropriate for fish, birds, or agricultural species used in research. Species-specific refinement requires deep knowledge of natural behaviour, social structure, cognitive capacity, and stress indicators for each taxon. Zebrafish, now widely used in research, have their own specific welfare needs that are still being characterised. Non-human primate welfare receives the most regulatory attention, but the same rigour should apply to all species. Continuous refinement - not just at initial study design but throughout research programmes - is the hallmark of genuinely welfare-conscious laboratory animal science.