Fish were long dismissed as simple reflexive animals. Decades of research have overturned this view, revealing cognitive and emotional complexity that demands welfare consideration.
The scientific case for fish welfare has been built over decades by researchers including Victoria Braithwaite, whose book asking Do Fish Feel Pain? synthesized the evidence comprehensively. Fish have the neural machinery for pain processing, show behavioral responses to noxious stimuli that are suppressed by analgesics, and demonstrate learning and memory that create the possibility of chronic suffering in poor conditions. The scale of fish use in aquaculture and fishing — hundreds of billions annually — makes their welfare one of the most numerically significant issues in applied animal ethics.