Tropical fish is now among handful of animal species that show 'self-awareness'

Researchers have discovered a tropical fish that has passed a classic test in self-awareness called the ‘mirror test’ or ‘mark test’.The study, pre-published in bioRxiv, uses a test developed in the 1970s by psychologist Gordon Gallup Jr.The test was designed to look for traits of visual self-recognition in non-human animals, and still used as a gold-standard for tests of self-awareness.The fish under study, a species of cleaner wrasse, are a tiny and tropical lot of Arctic Ocean-dwellers.Experts have known before the present study about the fish’s territorial nature, excellent eyesight, and their appetite for parasites residing on the bodies of other fish.Now, the fish joins the rank of a handful of animals to have passed the mark test other than humans — chimps, orangutans, bonobo monkeys, dolphins, elephants and pigeons.[caption id="attachment_5117971" align="alignnone" width="1280"]

Labroides dimidiatus, a species of the cleaner wrasse genus of fish that have been shown to have self-aware tendencies in the new study. Image courtesy: Wikimedia Commons[/caption]In this latest effort, researchers made a visible mark on the fish’s face, and introduced a mirror into its tank. Any movement or unusual behaviour that indicate attempts to touch or remove the mark are noted as signs of self-awareness.The fish reacted as the researchers expected them to — in defence mode, almost as if their territory is being encroached on, attacking the mirror. After being given some time to get accustomed to the mirror, the fish exhibited unusual behaviour, like bobbing while watching themselves in the mirror.The researchers repeated the same experiment with a gel mark that could only be seen if the fish looked directly at the mark in the mirror.They found the fish spending more time than before gazing at their reflections, even making attempts to scrape the gel off themselves. This behaviour, the researchers believe, qualifies as proof of the fish’s self-awareness as determined by the mirror test.However, the study is yet to be replicated and tweaked to verify the findings.The researchers admit to a possibility, however remote, that the fish could be attempting to grab what looks like yet another parasite to the fish — on their own bodies this time.