Striedter, Georg (2016) Lack of neocortex does not imply fish cannot feel pain. Animal Sentience. 3(15)
Brian Key, Why fish do not feel pain
Some contemporary scientists are using comparative neurobiological data to argue that non-mammalian vertebrates have feelings, most notably of pain (e.g., Braithwaite, 2010; Mashour and Alkire, 2012), while Key (2016) uses the same general data to reach the opposite conclusion. In a nutshell, he argues that fish cannot feel pain because fish don’t have a neocortex, which humans need to consciously experience pain. I don’t know how these scientists can look at essentially the same data and reach such disparate conclusions, but I suspect that some of them have strong a priori beliefs and, therefore, view the data through differently tinted spectacles. In any case, I think that both sides have overplayed their hands; the debate cannot be settled yet.