Hiodontidae

Hiodontidae is a small family of freshwater fish that includes only two extant species. These fish are commonly known as mooneyes and goldeyes. They are found in the freshwater systems of North America, primarily in Canada and the northern United States.

The family is characterized by its deep, laterally compressed body, large eyes, and a single, long dorsal fin. Their mouths are terminal and equipped with sharp teeth. Mooneyes, belonging to the genus Hiodon, typically have silvery bodies with a slightly darker back. Goldeyes, also in the genus Hiodon, are distinguished by their golden-hued scales.

These fish are carnivorous, feeding on smaller fish, insects, and crustaceans. They are often found in slow-moving or still waters, such as lakes, ponds, and rivers with muddy bottoms. Hiodontids are known for their ability to see well in low light conditions, which aids them in their nocturnal hunting.

The family Hiodontidae has a fossil record that extends back to the Cretaceous period, indicating a long evolutionary history. While the two living species are not considered endangered, their populations can be affected by habitat degradation and pollution. They are sometimes caught by anglers, though they are not a primary sport fish for most.