Do Fish Have Feelings?

Written by on December 7, 2015 in Fish, Marine Life

New research shows that zebrafish experience an “emotional fever” when subjected to stressful conditions, which could suggest a higher level of emotion and consciousness.


Zebrafish. Photo credit: Azul, CC BY-SA 3.0.

Researchers from the Universitat Autònoma de Barcelona (UAB) and the Universities of Stirling and Bristol recently observed that, when stressed, zebrafish experience an increase in body temperature of between two and four degrees. This increase in body temperature has been dubbed “emotional fever” and had never before been observed in fish.

To study this controversial phenomenon, researchers split 72 zebrafish into two groups and placed them in one large tank with temperatures ranging from 18 to 35 degrees Celsius in different compartments. One group (the control) was left undisturbed in a compartment with an ideal temperature of 28ºC. The other group was kept in a net inside an area that was a little cooler (27º) for 15 minutes. After being released from the net, these fish swam to compartments that were much warmer, therefore increasing their body temperature by a few degrees.

“These findings are very interesting: expressing emotional fever suggests for the first time that fish have some degree of consciousness,” Sonia Rey of the UAB’s Institute of Biomedicine and Biotechnology said in a news release.

Although, the idea of emotional fever and fish consciousness is highly controversial. Some scientists argue that due to the small, simple structure of a fish’s brain, there is no way they could exhibit consciousness. Others, however, contest that many morphological and behavioral analyses show that fish brains have similarities to other vertebrates and are, therefore, capable of displaying emotions.

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Copyright © 2015 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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