The Anostomidae are a family of fish that belong to order Characiformes (which are ray-finned fish). They are primarily found from southern Central America to South America. They usually have elongated bodies and small, apical to upturned mouths. Headstanders may orient themselves from 45 up to 90 degrees at times. This family contains twelve genera and at least 137 species.
This family is closely related to Chilodontidae.