How to Identify a Muskellunge (Esox masquinongy)

• Body shape: The largest of the pikes, the muskellunge is long and slender, with a mouth full of razor-sharp teeth.
• Cheek and gill-cover scales: Both the gill cover and cheek are scaled only on their upper halves, with a row of 6 to 9 pores along each side of the lower jaw (the northern pike's cheek, by contrast, is fully scaled).
• Body markings: Dark spots or bars on a light background (the opposite of the pike's light spots on a dark background); some individuals may show no distinct pattern at all.

The muskellunge has both cheek and gill cover scaled only on the upper half, and its sides usually show dark bars or blotches on a lighter background; the northern pike's cheek is fully scaled with only the gill cover half-scaled, and its sides show light spots on a darker background. See the Northern Pike page for its full mark list.

The muskellunge has no black bar beneath the eye, while the chain pickerel does — a useful way to tell them apart. See the Chain Pickerel page for its full mark list.

A freshwater fish that lives in lakes and pools of slow-moving streams, favoring clear water with abundant vegetation. Native within North America to the St. Lawrence River, Great Lakes, Hudson Bay (Red River), and Mississippi River basins.

Lay the fish flat on its side in even light and photograph the whole body first, then the details below. Photograph the gill cover and cheek straight on so the ear flap and scale rows are visible. Shoot the side of the body before the fish dries; spots and stripes fade fast out of water. 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.