Scientific understanding of fish sentience has advanced dramatically. The evidence for fish pain, fear, and individual variation in experience has important implications for how we treat the billions of fish used by humans annually.
Fish sentience research has fundamentally shifted the ethical landscape of aquaculture, fisheries, and research involving fish. The historical view that fish are simple, reflexive creatures incapable of subjective experience is contradicted by extensive evidence from neuroscience, behaviour, and physiology. Fish with hooks embedded show reduced feeding and altered behaviour even after the hook is removed — an effect eliminated by analgesic treatment, indicating pain-like experience rather than mere reflexive response. The welfare implications are substantial: billions of fish are used annually in food production, research, and recreational fishing without the welfare protections routinely applied to mammals and birds. Extending welfare consideration to fish is one of the most important frontiers in animal protection.