Carnegiella myersi is an odd and uncommon species of schooling fish from South America. Related to tetras and piranhas, hatchetfish have very deep, narrow bodies that serve as attachment points for extremely powerful pectoral muscles. Using these muscles, along with wing-like pectoral fins, hatchets can leap out of the water and glide several feet; an impressive feat for a fish that barely reaches an inch long! Obviously this means you should always keep hatchetfish with a lid, lest they jump out. Pygmy hatchets are a very peaceful species that spends most of their time at the surface of the water, making them a good choice to fill that oft-unused space in community aquaria. 

These are subadults around 0.5-0.75" long.