Scientific consensus on fish pain has shifted dramatically in recent decades, with growing evidence that fish are sentient and experience nociceptive distress, raising significant welfare questions for aquaculture.
The welfare implications of fish sentience for aquaculture are enormous. If fish experience pain and suffering - as the scientific evidence increasingly suggests - then the billions of fish raised and killed in aquaculture each year may be experiencing welfare harms that have been systematically ignored. Common aquaculture slaughter methods including suffocation, live chilling, and carbon dioxide stunning cause prolonged distress before death. Sea lice cause tissue damage that fish demonstrate aversion to. Crowding at commercial densities prevents normal behavioral expression and causes chronic stress. The scale of aquaculture - 90 million metric tons annually - means that even small improvements in fish welfare practices represent enormous aggregate welfare gains.