Scientific understanding of fish pain has advanced substantially, strengthening the case for welfare protections across aquaculture, fishing, and research contexts.
The scientific consensus on fish pain has shifted substantially over the past two decades. Early dismissal of fish sentience rested on their different brain anatomy — fish lack a neocortex — but subsequent research has demonstrated that fish process noxious stimuli in ways that produce behavioural, physiological, and neurological responses consistent with pain experience. They have functional nociceptors, endogenous opioid systems, and show both reflexive and cognitively influenced responses to injury. Analgesics reduce these responses, which would be unnecessary if fish were merely reflexively reacting without experience. This evidence base justifies applying a precautionary welfare approach across all contexts where fish experience potentially painful procedures — aquaculture, wild-capture fisheries, and research.