Slaughter methods for farmed fish vary widely in humaneness. Evidence-based welfare science supports pre-slaughter stunning as standard practice, but implementation remains inconsistent globally.
Fish slaughter welfare depends critically on whether fish are rendered insensible before painful death processes begin. Ice slurry chilling — one of the most common methods — causes a prolonged period of consciousness during which fish experience cold shock and suffocation. CO2 immersion causes aversive, distressing responses before unconsciousness. Electrical stunning and percussion stunning, when applied correctly to species-appropriate parameters, achieve rapid insensibility. The challenge is that optimal stunning parameters differ between species, requiring species-specific equipment and trained operators. The economic and logistical costs of better slaughter methods are modest relative to production costs, making consumer and regulatory pressure for improvement feasible. Progressive aquaculture operations are adopting best-practice methods voluntarily; regulatory standardisation would ensure baseline welfare across all producers.