AA << show that the cleaner wrasse fish, Labroides dimidiatus, passes through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror (contingency testing), and (iii) frequent observation of their reflection. >>
Masanori Kohda, Hatta Takashi, et al. Cleaner wrasse pass the mark test. What are the implications for consciousness and self-awareness testing in animals? BioRxiv doi: 10.1101/397067 Aug 21, 2018
https://www.biorxiv.org/content/early/2018/08/21/397067
<< Since the 1970s, a test developed by Gordon Gallup has been the gold standard for testing for self-awareness - researchers make a mark on a creature's face and introduce a mirror. If the animal makes some attempt to touch or remove the mark, they are deemed to have self-awareness. Since the test first came into use, only a few animals have ever passed the test. Besides humans, the list currently includes chimpanzees, bonobos, orangutans, dolphins, elephants and pigeons. >>
Bob Yirka. Small fish passes classic self-awareness test. Sep 4, 2018.
https://m.phys.org/news/2018-09-small-fish-classic-self-awareness.html