Scientific understanding of fish pain and sentience has advanced dramatically over two decades, with significant implications for how fish are treated in research, fishing, and aquaculture.
The scientific evidence for fish sentience and pain is now substantial. Fish show protective behavior after injury, seek analgesics when available, show sensitization to repeated injury, and demonstrate motivational tradeoffs between pain avoidance and other needs consistent with subjective experience. Yet the welfare of fish in commercial fisheries, recreational angling, and aquaculture receives far less attention than comparable harms to land vertebrates. Asphyxiation in air, a common commercial slaughter method, may take 4-15 minutes for fish to lose consciousness. Carbon dioxide stunning causes pain before unconsciousness. Percussion stunning and spiking (ike jime) can achieve rapid insensibility. The gap between what science shows and how fish are treated represents one of the largest unaddressed welfare challenges of our time.