Body shape : Elongate, more-or-less cylindrical, little or no lateral compression.

Average size : 20 to 30 cm (8 to 12 in), < 0.5 kg (< 1 lb); over 55 cm (21 in) and 1 kg (2 lb) in the St. Lawrence River

Coloration :  Varies according to habitat; dull gray to brown with 3 or 4 large, darker blotches extending from the back to the flanks (usually absent in clear water habitats); flanks with large black spots; 2 or 3 rows of black spots on first dorsal fin; rows of dark stripes on caudal fin; pearlescent eyes due to a reflective pigment layer.

External characteristics : Large eyes, cheeks with rough scales; numerous large, sharp teeth; 2 distinct dorsal fins, the first with 13 to 15 spines, the second soft-rayed; anal fin with 2 spines; one small spine at the superior edge of the operculum.