The scientific evidence for fish pain capacity has strengthened significantly in recent decades. Understanding this evidence is essential for making the welfare case for fish protection.
The evidence for fish pain capacity has crossed from scientifically uncertain to scientifically supported over the past 20 years. Fish possess the neuroanatomical structures required for pain processing, show behavioural responses to noxious stimuli that are modified by analgesics, demonstrate learned avoidance, and exhibit stress responses that parallel those of mammals. The debate has shifted from whether fish can feel pain to what the subjective experience of that pain is like — whether it involves conscious suffering comparable to mammalian experience. The welfare precautionary principle is clear: given the evidence, fish deserve welfare protections equivalent to other vertebrates.