Fish are slaughtered without stunning in most aquaculture operations worldwide, causing preventable suffering in animals with well-documented pain processing capacity.
Fish killed by asphyxiation in air take 4-15 minutes to lose consciousness while experiencing the acute distress of oxygen deprivation. Studies using behavioral indicators and brain activity measurements show fish maintain consciousness and respond to pain stimuli well into this period. The welfare case for pre-slaughter stunning in fish is as strong as for any other species, but regulatory frameworks lag behind the evidence. The precautionary principle demands treating fish death with the same welfare standards applied to mammals.