Can fish feel pain?

Most research in my sources says fish can feel pain, though the question is not fully settled. A systematic review of 349 scientific articles from 1990 to 2020 found six studies that tested pain in fish directly: five concluded that common carp, rainbow trout and goldfish can feel pain, and one was inconclusive1. The authors are affiliated with the animal welfare group World Animal Protection. Fish have pain receptors linked to the brain through nerve pathways, and brain activity has been measured when they meet something harmful2. Their brain is built like that of other vertebrates, but it is smaller and lacks the large cerebral cortex of mammals3, and some researchers still doubt that fish feel pain1. A 2010 report from fishcount.org.uk, a group working for fish welfare, notes that fish cannot tell us what they feel, but concludes that the balance of evidence says they do feel pain4.