Just read the abstract of the article [1]: "It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles),

Just read the abstract of the article [1]: "It has been suggested that the capacity for emotional fever evolved only in amniotes (mammals, birds and reptiles), in association with the evolution of consciousness in these groups. According to this view, lack of emotional fever in fishes reflects a lack of consciousness." The article is about "emotional fever", defined as "a transient rise in body temperature shown in response to a variety of stressors". Article shows that fish can show this behaviour. On the other hand, the "lack of consciousness" or its existence, is not proven. It is just a hypothesis, based on some "view", expressed in [2]. [1] http://rspb.royalsocietypublishing.org/content/282/1819/20152266 http://rspb.royalsocietypublishing.org/content/282/1819/2015... [2] http://dx.doi.org/10.2170/jjphysiol.49.1 http://dx.doi.org/10.2170/jjphysiol.49.1