Evidence for fish pain capacity has grown substantially over two decades, fundamentally changing how welfare scientists and regulators approach farmed fish welfare.
The question of whether fish feel pain has moved from contested to broadly accepted in welfare science. Fish have nociceptors, produce endogenous opioids, show learned avoidance of painful stimuli, and display behavioral changes under noxious stimulation that are reduced by analgesics. The welfare implications are profound given the billions of fish farmed annually, the stocking conditions, handling practices, and slaughter methods common in commercial aquaculture. Incorporating pain management into farmed fish welfare standards is one of the most significant outstanding opportunities in food system welfare improvement.