Most farmed fish worldwide are killed without any prior stunning, meaning they likely experience distress and pain during slaughter. Effective fish stunning technology exists but is not yet universally adopted.
The slaughter of farmed fish without prior stunning represents one of the largest scale welfare problems in animal agriculture measured by individual animals affected. A fish killed by asphyxiation in air or live on ice may remain conscious for several minutes during which it experiences oxygen deprivation and physical distress. The scale — tens of billions of fish slaughtered annually in aquaculture alone — makes improvements in stunning adoption enormously impactful in terms of suffering reduced per intervention. Technology exists; the barriers are largely economic and regulatory. Investment in lower-cost, reliable stunning equipment and clearer regulatory requirements could prevent enormous quantities of suffering.