Like other gizzard shads, the body is deep somewhat forward of the middle. It is a grayish or silvery blue above, becoming silver on the sides and white below. The dorsal fin has 10-12 rays; in adults, the last ray is very long, extending beyond the rest of the fin. The caudal fin is deeply forked. They can reach a length of 57 cm, and weigh up to nearly 2 kg.
American gizzard shad begin life feeding on zooplankton, using their teeth to catch them. At about 1 inch in length, they lose the teeth, become deeper-bodied, develop the muscular gizzard, and become filter feeders, consuming both small invertebrates and phytoplankton, as well as some sand for the gizzard.
They live in a variety of open waters, both clear and silty, including rivers, swamps, lakes, and bays, typically near the surface. They avoid fast-moving water.
Native range extends from the Great Lakes and St. Lawrence River area west to eastern South Dakota and central New Mexico, as well as to the Gulf of Mexico, where it has been found as far south as Rio Panuco in Mexico.
The specific epithet cepedianum honors French naturalist Bernard Germain Étienne de La Ville-sur-Illon, comte de Lacépède (1756-1825).