any of several species of small, slim schooling fish of the family Atherinidae (order Atheriniformes), found in freshwater and along coasts around the world in warm and temperate regions.

Silversides are named for the wide, silvery stripe usually present on each side. They have two dorsal fins and range in length to about 70 cm (28 inches). They are sometimes harvested for food.

The grunion (Leuresthes tenuis), a small species (15 cm long) found along California coasts, is noted for its spawning runs. It breeds along beaches at night, coming ashore at high tide. The eggs are buried in the sand, and, at the next high tide, they hatch and the new young make their way into the sea.