Hatchetfish are the freshwater counterparts of the sea-dwelling flying fish. However, hatchetfish go a significant step further; they can genuinely fly, instead of simply gliding above the water.
Freshwater hatchetfish are sometimes called flying characins; a direct reference to the technique they use to escape predators. When threatened, they shoot out of the water and, quite literally, disappear. This usually confuses a predator sufficiently to allow the hatchetfish to escape.
