The welfare of farmed fish at slaughter is a significant and growing concern as aquaculture production increases, with most species currently killed by methods that cause prolonged consciousness and distress.
The welfare of farmed fish at slaughter is arguably the largest-scale unaddressed animal welfare problem in agriculture by number of animals affected. Asphyxiation in air causes fish to experience progressive oxygen deprivation over several minutes before losing consciousness. Carbon dioxide is aversive and causes distress before inducing unconsciousness. Live chilling on ice may maintain consciousness for extended periods. The fact that fish welfare at slaughter receives limited regulatory attention despite overwhelming numbers reflects a combination of historical attitudes toward fish sentience and the practical challenges of developing species-specific stunning methods. High-welfare slaughter methods for salmon and trout exist and are commercially viable, demonstrating that improvement is achievable.