Seen head-on when open, the mouth gap covers most of the frontal area of the fish and the large number of gill rakers which retain ingested food are evident. There are one to three rows of dark spots along the side between the gill cover and the dorsal fin, which become progressively smaller towards the posterior. After a short period in freshwater for spawning, shad take on a bronze or coppery hue and the head and ventral portions of the body become red, especially among males. Young shad in freshwater are silvery with a blue-green back. Mature shad are 40 to 60 cm in length and weigh 1 to 3 kg.
Females are usually larger than males.
The largest shad seen by Canadian biologists in recent years was 75 cm long and weighed 4.2 kg. The natural range of spawning populations of American shad is from the St. Lawrence River, Quebec to the St. John's River, Florida. During summer, shad are found in the sea as far north as central Labrador. Large populations occur in the Annapolis, Shubenacadie, Miramichi and St. Lawrence rivers. Shad were introduced to the Pacific coast in 1871 in the Sacramento River in California and have become established from California to Alaska.