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 Thwaites Glacier, Antarctica
Image of the day: Thwaites Glacier retreat in AntarcticaNews

Image of the day: Thwaites Glacier retreat in Antarctica

Covering about 120 kilometres in width, the Thwaites Glacier in West Antarctica plays a critical role in regulating global sea levels. It drains a large…
Muser NewsDeskMuser NewsDeskOctober 6, 2025 Full article
Image: aerial view of Aarhus Ø, Denmark
Flood risk assessment expands to 51 municipalities across DenmarkNews

Flood risk assessment expands to 51 municipalities across Denmark

The number of municipalities in Denmark identified as being at significant potential risk of flooding has nearly doubled, increasing from 27 to 51. This sharp…
Muser NewsDeskMuser NewsDeskDecember 20, 2024 Full article
3d electric car charging at station
Carmakers to push EU for 2035 combustion-engine ban rethinkNews

Carmakers to push EU for 2035 combustion-engine ban rethink

Brussels, Belgium | AFP | Muser NewsDesk Europe's biggest carmakers are to hold talks with EU chief Ursula von der Leyen on Friday as the industry…
SourceSourceSeptember 12, 2025 Full article