Marine Wildlife Encyclopedia
Allis Shad Alosa alosa
The Allis shad is a silvery fish belonging to the herring family (Clupeidae) and is one of the few that enter fresh water. During April and May, mature adults migrate into rivers to spawn, swimming up to 500 miles (800 km) upstream. In some parts of its range, the Allis shad is known as the May fish. Its streamlined body is covered by large circular scales that form a keel under the belly, and it has a single dorsal fin. The Allis shad is now very rare over much of its range.