The scientific debate over fish pain has largely resolved in favor of acknowledging fish capacity for pain-like experience, with major welfare implications.
The scientific consensus on fish pain has shifted dramatically over the past two decades. Early skepticism based on fish lacking a neocortex has given way to recognition that consciousness and pain processing can operate through different neural architectures. Fish show behavioral and physiological responses to noxious stimuli that parallel those of mammals, and opioid analgesics reduce these responses in ways consistent with genuine pain relief. The welfare implications are staggering given the scale of fish in fishing and aquaculture — even modest improvements in how fish are handled and killed would benefit enormous numbers of individuals.