How to Identify a Walleye (Sander vitreus)

• Body shape: The walleye is a slender, spiny-rayed fish with two separate dorsal fins.
• Dorsal fin: The spinous dorsal fin is streaked and blotched with black, usually with a large black blotch near the bases of the last few spines.
• Tail shape: The lower tip of the tail is white, unlike the all-dark lower lobe of the sauger.
• Jaw length: The mouth is large, with the upper jaw extending about to the hind edge of the eye; the jaws and roof of the mouth have prominent teeth.
• Eyes: The walleye is named for its pearlescent eye, caused by the tapetum lucidum, a reflective layer of pigment.

The lower tip of the walleye's tail is white, unlike the all-dark lower lobe of the sauger's tail; the walleye's dorsal fin has one large black blotch, while the sauger's has rows of small black spots; the walleye's sides show little patterning, while the sauger has distinct dark saddle-shaped blotches on the sides. See the Sauger page for its full mark list.

A freshwater fish that inhabits open water of lakes and reservoirs and the pools of streams. Native to freshwater rivers and lakes of the northern United States and Canada, with a historical range roughly forming a triangle bounded by the St. Lawrence-Great Lakes, Mississippi River, and Arctic drainages.

Lay the fish flat on its side in even light and photograph the whole body first, then the details below. Spread the tail fin so its shape (forked, rounded or square) is clear. Get a close, sharp frame of the head: mouth, jaw length and any barbels. Raise the dorsal and anal fins fully; ray counts and fin edges only read when the fin is spread. The app reads the photo and names the likely species; use the marks on this page to confirm it.

Size and daily limits for this species differ by state and by water, and some waters are catch-and-release only. Check the current regulations for where you are fishing before keeping any fish; if you are unsure of the species, release it.