This European committee said that a fish's nervous system is similar to that in higher vertebrates, and that their skin has receptors for pain.
"In accordance with Article 9, paragraph 3 of the Convention, this Recommendation entered into force on 5 June 2006"
"The basic structure and function of muscles, liver, hormonal control mechanisms and nervous system are similar to higher vertebrates."
"The skin of the fish is the first line of defence against disease and provides protection from the environment. It contains sensory receptors for touch, pressure and pain and also has respiratory, excretory and osmoregulatory functions."