After subjecting a group of zebrafish to stressful situations, they suffered an increase in body temperature of between 2 and 4 degrees , according to a team of researchers from the Autonomous University of Barcelona, together with scientists from the Universities of Barcelona. Stirling and Bristol (UK).
It is a phenomenon called emotional fever, which is related to the emotions that animals feel when faced with an external stimulus. It has even been associated with some degree of consciousness, although this is a controversial issue. Emotional fever had been detected in mammals, birds and some reptiles, but never in fish , which were considered animals without emotions or conscience. This new study, carried out with 72 specimens of zebrafish, has altered this idea.
The researchers divided the fish into two groups of 36 specimens and placed them in a large tank with different intercommunicating compartments, with temperatures ranging from 18ºC to 35ºC. The fish of the control group remained in the zone that was at their preferred temperature: 28 ºC, and without being subjected to any special action. The fish from the other group were put through a stressful situation: they were confined for 15 minutes in a net inside the tank, at 27 ºC. After this time, they were released.
While the control fish remained in the 28 ºC compartments, the stressed fish moved to the heated tanks and increased their body temperature by between 2 ºC and 4 ºC. For researchers, it is an emotional fever expression test. Scientists are very divided on the degree of consciousness of fish. Some researchers believe that they cannot have it because of the simplicity of their brains, which lack cerebral cortex, memory and learning capacity , with a very limited repertoire of behaviors and without the capacity to experience suffering.
Others, on the other hand, point out that, despite its small brain, detailed analysis of its morphology and behavior shows similarities with other vertebrates. For example, there are certain analogies between the hippocampus of fish (related to spatial learning and memory) and the amygdala (related to emotions) of mammals.
