I added eight of these to my office aquarium today.
They are called spotted hatchetfish and are one of only a few species of fish that can actually fly. They do so by flapping they enlarged pectoral fins. This obviously requires quite a bit of power which is why these fish have such a weird shape (aerodynamics, attachment of muscles for powering flight). Mine are already settling into their new environment, darting around the roots of the water lettuce, and hanging out near the top portion of the aquarium.