The scientific evidence that fish experience pain has strengthened substantially over the past two decades. Understanding this evidence is the foundation for taking fish welfare seriously.
The weight of evidence now strongly supports the conclusion that fish have nociceptive systems capable of producing something functionally similar to pain in mammals. Whether their subjective experience of pain is comparable to human pain remains philosophically uncertain — but this uncertainty cuts both ways. Given the scale of fish used in aquaculture and caught in fisheries, a precautionary approach that minimises fish suffering is scientifically and ethically justified. The history of animal welfare shows that species dismissed as unable to feel pain — initially lobsters, then fish — are repeatedly shown to have more sophisticated nociceptive systems than assumed.