Most farmed fish are slaughtered using methods that cause prolonged suffering before death — humane slaughter is technically feasible but not yet standard practice.
Fish welfare at slaughter is one of the largest-scale welfare issues in animal agriculture. The numbers involved are staggering — billions of fish per year — and the predominant methods cause death by slow asphyxiation or freezing, both of which take many minutes and involve sustained conscious suffering. Humane alternatives — percussive stunning, electric stunning, carbon dioxide followed by percussion — exist and have been implemented at scale in some salmon industries. The gap between what is possible and what is practiced represents an enormous, addressable welfare burden.