Rainbow trout are among the best-studied fish species in terms of pain science, and the evidence has direct implications for welfare in aquaculture settings.
The evidence base for rainbow trout experiencing pain is among the strongest for any fish species. Landmark studies by Victoria Braithwaite and colleagues demonstrated that trout respond to noxious stimuli with both behavioral changes (rocking, rubbing) and physiological stress responses that are attenuated by analgesics. This pain-relevant evidence base has directly informed regulatory changes. Welfare implications for trout aquaculture include humane slaughter requirements, minimization of handling and crowding, and avoidance of practices causing tissue damage. The trout evidence base is used to support precautionary welfare consideration for other fish species.