Although typically we associate emotions only to a handful of animal, emotional fever may be attributed to mammals, birds and certain reptiles. It is an increase in body temperature when subject is in a stressful situation. Now this phenomenon was for the first time observed in fish.
Scientists from the Universitat Autònoma de Barcelona, together with scientists from the universities of Stirling and Bristol, for the first time observed increasing body temperature in zebrafish when they were placed in a stressful situation. Temperature increased only by 2-4 degrees, but emotional fever has never been observed in fish before, which makes it significant. Even more so, because emotional fever is linked not only to the animal having emotions, but also consciousness.
Fish has been regarded as an animal without any emotions or consciousness. However, this new experiment, involving 72 zebrafish now is questioning this concept. The experiment in itself had rather interesting methodology – animals were divided into two equal groups and placed in in a large tank with different interconnected compartments with temperatures of 18-35 degrees Celsius. Control group remained still in the temperature of 28 degrees that they prefer. The experimental group, however, was confined in a net for 15 minutes at 27 degrees. When released they rushed to the warmer compartments of the tank, raising their body temperature by 2-4 degrees Celsius.
However, does it really mean that fish have consciousness? Some scientists point out it being impossible because of very simple brain without a cerebral cortex, limited learning capacity and behavioural repertoire and no ability to experience suffering. Other scientists question this view by arguing that there are needed elements in very simple brain of the fish that resemble those of vertebrates.
Sonia Rey, one of the authors of the study, said: “these findings are very interesting: expressing emotional fever suggests for the first time that fish have some degree of consciousness”. However, more evidence is needed and scientific community will not be convinced by such preliminary evidence.