The study of evolutionary development indicates that the pallium in the forebrain of fish is similar to the hippocampus, amygdala and neocortex of land vertebrate animals. These are important areas in the processing of pain.
"Broad areas equivalent to those of land vertebrates can be recognized in the central nervous system of fishes. Phylogenetic¹ analysis indicates that the main subdivisions of the pallium in the actinopterygian telencephalon are probably homologous to the hippocampus, the amygdala and the neocortex of tetrapods."
¹ phylogenetic = relating to the evolutionary development of organisms