Before squaring up for a fight, some fish check themselves out in the mirror to make sure they're big enough. This strange behavior was seen in bluestreak cleaner wrasse (Labroides dimidiatus), who ...

Controversial new research shows that a tiny, unsuspecting species of fish can pass a test that’s widely considered the gold standard of intelligence. As far as we can tell, only a few of the most ...

Bluestreak cleaner wrasse are small, territorial fish that aggressively fend off intruders. But when they have access to a mirror, the fish size themselves up before deciding whether or not to fight.

Mirror tests are used to assess an animal’s response to its reflection. Explore how fish react and learn if they possess self-awareness. In February, a team of researchers published a paper showing ...

Alex Jordan had just surfaced from a dive off the coast of Corsica when he called me back last summer. “We’ve put mirrors in the wild,” he said. “It’s always a bit of a nightmare.” With the help of ...

Cleaning behavior is found in all tropical reef communities. The cleaner wrasse, Labroides dimidiatus, is one of the many organisms that display this behavior. The cleaning stations, which were ...