Fish can show emotional fever: stress-induced hyperthermia in zebrafish.
Sonia Rey, Felicity A Huntingford, Sebastian Boltaña, Reynaldo Vargas, Toby G Knowles, Simon Mackenzie
Proceedings of the Royal Society B: Biological Sciences November 1, 2015 DOI: 10.1098/rspb.2015.2266 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Controlled laboratory experiment Peer reviewed |
|---|---|
| Population | Zebrafish (Danio rerio), studied in six groups |
| Duration | A short period of confinement |
| Keywords | Animals Zebrafish Body temperature Stress, psychological Emotions Consciousness Hot temperature Stress-induced hyperthermia Fish welfare Emotional fever Fish sentience |
| Key findings | Stressed zebrafish with access to a temperature gradient spent significantly more time at higher temperatures than undisturbed controls, achieving an estimated body temperature rise of about 2-4°C. The authors argue this demonstrates that zebrafish can show 'emotional fever', removing a key argument that fishes lack consciousness, while noting the link between emotion and consciousness is still debated. |
Abstract
Whether fishes are sentient beings remains an unresolved and controversial question. Among characteristics thought to reflect a low level of sentience in fishes is an inability to show stress-induced hyperthermia (SIH), a transient rise in body temperature shown in response to a variety of stressors. This is a real fever response, so is often referred to as 'emotional fever'. 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. We report here on a study in which six zebrafish groups with access to a temperature gradient were either left as undisturbed controls or subjected to a short period of confinement. The results were striking: compared to controls, stressed zebrafish spent significantly more time at higher temperatures, achieving an estimated rise in body temperature of about 2-4°C. Thus, zebrafish clearly have the capacity to show emotional fever. While the link between emotion and consciousness is still debated, this finding removes a key argument for lack of consciousness in fishes.