Humane killing of fish at the end of their productive lives or for disease management is an often-overlooked welfare challenge in aquaculture, with significant variation in method quality.
Fish euthanasia welfare is a largely invisible issue in aquaculture that affects millions of fish annually. Disease outbreaks requiring population culling, end-of-productive-life mortality, and research animal euthanasia all require humane killing methods. Poorly chosen methods cause prolonged suffering before death. Carbon dioxide exposure, commonly used due to cost and convenience, causes significant distress in many fish species. Percussive stunning followed by pithing or gill cutting is more welfare-positive for many species. Veterinary guidance and species-specific protocols are needed to improve this neglected aspect of aquaculture welfare.