This ia an amazing development! A cleaner fish has passed the mirror test. The mirror test is used to determine self-awareness in animals. The animal has to do something to demonstrate that it knows that the reflection in the mirror is actually themselves. Only a couple of advanced animals besides humans have passed the test previously. Of course the fact that a fish passed the test has some scientists wondering if the mirror test itself is not valid. Interesting.
Here is the article: Quanta Magazine