Fish welfare research has advanced dramatically in the past two decades, revealing capacities once thought impossible in non-mammalian vertebrates.
The scientific case for fish sentience has strengthened dramatically since the 2000s when fish welfare was widely dismissed. Nociceptor studies, opioid receptor research, and behavioural experiments showing genuine pain responses have converged into a strong scientific consensus: fish almost certainly experience something when harmed. The scale of fish use — vastly exceeding all other farmed animals combined in numbers — means even a modest probability of sentience creates an enormous welfare obligation. Fish welfare policy is decades behind the science.