There are 245 species in six families in this order of fish. They are sometimes called “bony-tongued” fish because they have teeth on their tongues, which help them catch and hold food. Most of these fish live in freshwater rivers and lakes in Africa, South America, Asia, and Australia.

They vary a lot in size and shape. The smallest, the dwarf stonebasher (Pollimyrus castelnaui), is only 0.79 inches (2 cm) long, while the largest, the arapaima (Arapaima gigas), can grow up to 8 feet (2.5 m) long.

Osteoglossiformes have strong, bony skeletons, long bodies, and large scales. Some, like the elephantnose fish, use electric signals to communicate and navigate in dark water. Many are predators, feeding on insects, smaller fish, and other small animals.