Fish size themselves up in a mirror to decide if they can win a fight
Cleaner wrasse use their reflection to build a mental image of their body size, which they use to compare themselves to rivals before picking a fight
Before deciding whether or not to fight another fish, cleaner wrasse check their own reflection in a mirror and size themselves up. Bluestreak Cleaner Wrasse (Labroides dimidiatus) are remarkably bright. These finger-sized coral reef fish were the first fish to pass the mirror test, a common assessment to see whether an animal recognises that the reflection is of its own body and not another animal. Researchers have now found that these wrasses use their likeness to construct a mental image of their body size, which they can compare to others...
Read more: https://www.newscientist.com/article/2447414-fish-size-themselves-up-in-a-mirror-to-decide-if-they-can-win-a-fight
