A tiny fish from the cleaner wrasse (Labroides dimidiatus), a finger-sized marine fish, has passed a mirror test, which tests animal self-recognition to determine how similar other species' intelligence might be to our own. The tests, which are often used to identify other animals' marks on their own bodies, were initially reported to have passed in 2018. However, a team from Osaka Metropolitan University in Japan and the University of Neuchâtel in Switzerland has tweaked the experiment to further test the fish's self-awareness even further. They found that the fish recognized itself in the reflection and used a piece of food to explore the mirror's workings. The findings suggest that self-aware, once thought to be a skill once distinguished Great Apes, may have evolved in a wider range of animals, including fish, at a minimum with the bony fishes at 450 million years old and likely widespread across vertebrates.