Most farmed and wild-caught fish are killed without stunning, experiencing potentially prolonged suffering. Evidence-based stunning methods exist and are increasingly required by welfare standards.
Fish slaughter welfare represents one of the largest gaps between evidence and practice in the entire animal welfare field. The number of fish killed annually for food dwarfs all other vertebrate animal deaths combined, yet the majority die without any form of stunning. Common practices — leaving fish to suffocate in air, immersing in CO2 which causes aversive gill irritation, or live chilling — all involve prolonged consciousness before death if fish experience aversive states. Validated stunning methods exist for major aquaculture species: percussive stunning, electricity, and anesthetics all cause rapid insensibility. The barrier to adoption is primarily economic and cultural rather than technical. Norway's mandatory salmon stunning requirement demonstrates that welfare-compliant fish slaughter is commercially viable.