title: Fish can show emotional fever: stress-induced hyperthermia in zebrafish.
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.
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain sonia.reyplanellas@stir.ac.uk.
authors.forename: Sonia
authors.identifier: http://orcid.org/0000-0002-3406-3291
authors.initials: S
authors.lastname: Rey
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Felicity A
authors.initials: FA
authors.lastname: Huntingford
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Boltaña
authors.affiliation: Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: Reynaldo
authors.initials: R
authors.lastname: Vargas
authors.affiliation: School of Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, UK.
authors.forename: Toby G
authors.initials: TG
authors.lastname: Knowles
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: Simon
authors.initials: S
authors.lastname: Mackenzie
mesh_terms: D000818:Animals; D001831:Body Temperature; D003243:Consciousness; D004644:Emotions; D006358:Hot Temperature; D013315:Stress, Psychological; D015027:Zebrafish / Q000502:physiology*
keywords: consciousness; emotional fever; fish sentience; fish welfare; stress-induced hyperthermia; zebrafish