The question of whether fish can experience pain has moved from philosophical debate to scientific consensus, with important implications for how billions of animals are treated.
The scientific evidence that fish experience pain has strengthened substantially over the past two decades. Studies show that fish seek analgesics when in pain, avoid conditioned stimuli associated with harm, and show physiological stress responses to injury. The absence of a neocortex does not preclude pain experience, as alternative neural pathways serve analogous functions. This evidence has driven welfare reforms including mandatory stunning before slaughter in some jurisdictions. The scale of fish use in human food systems means that even marginal improvements in welfare practices affect billions of individuals.