The majority of farmed fish are still killed without prior stunning, meaning they die conscious. Effective stunning technology exists and is increasingly being adopted under welfare pressure.
Death by asphyxiation is among the most welfare-compromising aspects of fish aquaculture, yet it remains standard practice for most farmed fish species globally. Fish subjected to asphyxiation or CO2 exposure show clear stress responses including increased opercular rate, escape attempts, and loss of equilibrium over extended periods before death. The duration of conscious distress during asphyxiation can exceed 15 minutes in salmon. Effective percussive or electrical stunning renders fish insensible within seconds, dramatically reducing suffering at slaughter. The technology exists, the science is clear, and the costs of adoption are declining. Regulatory requirements and consumer pressure are the primary drivers of adoption where voluntary uptake has been insufficient.