Decades of research have established that fish experience pain and other aversive states, fundamentally changing how we should regard their welfare.
The scientific case for fish sentience and pain experience has grown substantially since the early 2000s. Key research by Victoria Braithwaite, Lynne Sneddon, and others documented pain-relevant anatomy, pain behaviors, and pharmacological responses in fish. Skeptics argued that fish lacked the neocortex considered necessary for conscious pain, but neuroscientists have identified functionally equivalent structures in fish brains. The scientific consensus has shifted significantly toward accepting fish as sentient animals capable of suffering. This has profound implications for fisheries, aquaculture, and the billions of fish handled with minimal welfare consideration.