Researchers have found evidence of self-awareness in the cleaner fish Labroides dimidiatus through use of the Mirror Self-Recognition (MSR) test.

The MSR test involves placing a mark on the animal’s body which can only be indirectly viewed through a mirror, and when seeing themselves in a mirror, they then attempt to touch or scrape the mark location.

The research, carried out by researchers at Osaka City University, found that after placing a brown mark on the throat area of 18 cleaner fish, 17 (94 per cent) attempted to scrap their throats several times after swimming in front of a mirror.

Professor Masanori Kohda from the Graduate School of Science, Osaka City University, explained the reason for using a brown mark.

“After looking at similar studies done on monkeys, pigs, dogs, cats, etc. that clearly tested negative, we wondered if the reason these animals didn’t attend to the mark was because it didn’t represent something in their natural environment they would be concerned about.”