The standard test for self-awareness has been to make a mark on a creature’s face and introduce a mirror. If the creature attempts to touch or remove the mark, they are deemed to be self-aware. Few animals have ever passed the test including humans, chimpanzees, bonobos, orangutans, dolphins, elephants and pigeons and now a tiny wrasse.
https://phys.org/news/2018-09-small-fish-classic-self-awareness.html