What if that proverbial man in the mirror was a… fish? Would it change its ways? According to an Osaka Metropolitan University-led research group, the answer is yes.

muser Kobayashi
A bluestreak cleaner wrasse (Labroides dimidiatus) swims in a tank at right, with its mirror image at left. Credit: Osaka Metropolitan University

In what researchers describe in Scientific Reports as the first demonstration of a non-human animal possessing certain mental states (e.g., mental body image, standards, intentions, goals), which are elements of private self-awareness, bluestreak cleaner wrasse (Labroides dimidiatus) checked their body size in a mirror before deciding whether to attack fish that were slightly larger or smaller than themselves.

The team – consisting of OMU Graduate School of Science student Taiga Kobayashi, Specially Appointed Professor Masanori Kohda, Professor Satoshi Awata, Specially Appointed Researcher Shumpei Sogawa, and Professor Redouan Bshary of Switzerland’s University of Neuchâtel – was also part of the group that last year reported the cleaner wrasse could recognize photographs of themselves, using their face through mirror self-recognition.

This time, the cleaner wrasse’s behavior of looking into a mirror installed in a tank when necessary suggested that the fish were using the mirror to check their own body size relative to other fish and predict the outcomes of potential fights.

“The results that fish can use the mirror as a tool can help clarify the similarities between human and non-human animal self-awareness and provide important clues to elucidate how self-awareness has evolved,” doctoral candidate Kobayashi declared.

***

This study was financially supported by JST SPRING (JPMJSP2139 to T.K.), JSPS KAKENHI (23KJ1829 to T.K., 19F19713 and 20K20630 to M.K., 22H02703 to S.A., and 20K20154 to S.S.), Swiss Science Foundation (310030_192673 to R.B.), and an OCU Strategic Research Grant 2018–2019 (to M.K. and S.A.).

Journal Reference:
Taiga Kobayashi, Masanori Kohda, Satoshi Awata, Redouan Bshary, Shumpei Sogawa, ‘Cleaner fish with mirror self-recognition capacity precisely realize their body size based on their mental image’, Scientific Reports 14, 20202 (2024). DOI: 10.1038/s41598-024-70138-7

Article Source:
Press Release/Material by Osaka Metropolitan University
Featured image credit: François Libert | Flickr | CC BY-NC-SA

Satellite Image: The Isle of Pines, New Caledonia
Image of the day: Wildfire extent on New Caledonia’s Isle of PinesNews

Image of the day: Wildfire extent on New Caledonia’s Isle of Pines

The Image of the day shows the wildfire extent on New Caledonia’s Isle of Pines, where a large fire that began on 30 November 2025…
Muser NewsDeskMuser NewsDeskDecember 9, 2025 Full article
Image: International event logo
USP and FAPESP bring innovative technologies to international startup fair in FranceNews

USP and FAPESP bring innovative technologies to international startup fair in France

VivaTech is one of Europe's leading technology and startup events; USP and FAPESP will take researchers and disruptive technologies to the event in the areas…
SourceSourceJune 6, 2025 Full article
Image: cargo ship on sea during daytime (s. maritime emissions)
US threats cast doubt on shipping emissions dealNews

US threats cast doubt on shipping emissions deal

London, United Kingdom | AFP | Muser NewsDesk An ambitious plan by the UN's shipping agency to cut maritime emissions could be scuttled at the last…
SourceSourceOctober 14, 2025 Full article