Stunning fish before slaughter is critical to preventing conscious suffering during killing, with electrical, percussive, and CO2 methods varying considerably in their welfare effectiveness.
Fish that are not stunned before slaughter are conscious during killing procedures that may include asphyxiation, gill cutting while conscious, and CO2 exposure. This can cause prolonged suffering over minutes. The scale of farmed fish production - billions of fish annually - means the welfare impact of inadequate stunning practices is enormous. Growing scientific consensus that fish experience pain and distress obligates the industry to adopt effective stunning before slaughter. Consumer and retailer pressure has begun driving improvements, but comprehensive regulatory requirements for fish stunning remain absent in most jurisdictions.