Most farmed fish are killed without prior stunning, experiencing what evidence suggests is significant pain and distress. Improving slaughter methods is one of the most tractable welfare interventions in aquaculture.
Fish almost certainly experience pain and fear during slaughter, and methods that avoid stunning cause prolonged distress. Carbon dioxide immersion, the most common commercial method, causes a period of apparent aversion before unconsciousness. Live chilling on ice, used for many species, causes a slow death lasting minutes. The cost of implementing effective electrical or percussive stunning is relatively low in aquaculture operations, making this a highly tractable welfare improvement. Consumer demand for labelled higher-welfare fish has begun to drive market uptake.