Hatchetfish is the common name for two distinct groups of fish with similar hatchet-shaped bodies. Freshwater hatchetfish live near the surfaces of rivers and ponds in Central and South America. Marine hatchetfish inhabit moderately deep ocean waters around the world. Both groups have compact heads and deep, protruding chests.
Freshwater hatchetfish grow from 1 to 4 inches (2.5 to 10 centimeters) in length. They are the only fish that can truly fly. Their powerful pectoral (chest) muscles enable them to move their long pectoral fins quickly. The fins act as wings and can propel the fish as far as 10 feet (3 meters) in the air to avoid predators. Freshwater hatchetfish use their upturned mouths to feed at the water’s surface. Insects serve as their main source of food.
Marine hatchetfish grow up to 4 inches (10 centimeters) long. They have a silvery color, upward-pointing eyes, and special light organs on the underside of the body. Light produced by these organs shines downward and helps camouflage the fish from predators. Predators from below see only the light, while predators from above fail to detect the fish’s dark back, which blends in with the dark ocean environment. Marine hatchetfish typically eat small or immature fish.
