The sauger (Sander canadensis) is a freshwater perciform fish of the family Percidae that resembles its close relative, the walleye. The species is a member of the largest vertebrate order, the Perciformes. It is the most migratory percid species in North America. Saugers have two dorsal fins; the first is spiny and the posterior dorsal fin is soft-rayed. Their paired fins are in the thoracic position and their caudal fin is truncated, which means squared off at the corners, a characteristic of the family Percidae. Another physical characteristic of saugers is their ctenoid scales, which are common in advanced fishes. Saugers have a fusiform body structure, and as a result are well adapted predatory fishes and are capable of swimming into fast currents with minimal drag on their bodies. They may be distinguished from walleyes by the distinctly spotted dorsal fin, by the lack of a white splotch on the caudal fin, by the rough skin over their gills, and by their generally more brassy color, or darker (almost black) color in some regions. The typical sauger is 300 to 400 g (11 to 14 oz) in weight.