Pain assessment in fish is particularly challenging due to their evolutionary distance from humans, their lack of audible vocalization, and apparently expressionless demeanour. However, there are criteria that can be used to gauge whether pain perception occurs using carefully executed scientific approaches. Here, the standards for pain in fish are discussed and can be considered in three ways: neural detection and processing of pain; adverse responses to pain; and consciously experiencing pain. Many procedures that we subject fish to cause tissue damage and may give rise to the sensation of pain. Fish are popular as pets, in animal exhibits, and as experimental models, but are also cultured or caught for food. There is little legislation for the protection of fish welfare. Many countries are now exploring the welfare cost to fish, and current practices may need to be reviewed with respect to the current evidence for fish perceiving pain.
Sneddon, L. (2011). Pain perception in fish. Journal of Consciousness Studies, 18(9-10), 209-229.