The fish that lives in trees and breeds without a mate
The mangrove rivulus, also known as the mangrove killifish, is native to the Americas and is about five centimetres (two inches) long.
The fish has long been studied for its many unique features. It's the only vertebrate known to naturally self-fertilize, for example. In some populations, it can become a hermaphrodite, developing both male and female parts simultaneously, to produce clones of itself.