How to Identify a Lake Trout (Salvelinus namaycush)
Quick answer
Lake Trout, Salvelinus namaycush: the 4 field marks to check, size, habitat and North American range, with sources. How to tell it from Brook Trout.
Updated 2026-09-10 · Sources: dnr.wisconsin.gov, U.S. Fish & Wildlife Service
Found one? Take a photo to identify it.
Download on the App StoreWhat are the key facts?
- Scientific name: Salvelinus namaycush
- Family: Salmonidae (Trout)
- Adult size: Length is commonly about 17-36 inches (about 43-91 cm); weight is commonly about 3-30 pounds (about 1.4-13.6 kg).
- Habitat: Most lake trout inhabit deep lakes greater than 50 feet, though they can be found at depths well over 200 feet, as well as in deep tributary channels connecting to large lakes.
- Range in North America: Native to northern North America, from Alaska to Nova Scotia and throughout the Great Lakes.
Key marks to check on a Lake Trout
- Tail shape: Lake trout are distinguished by having a deeply forked tail.
- Mouth and anal fin: The inside of the mouth is white, and the anal fin has 10-11 rays.
- Body markings: Color varies from light green or gray to dark green or almost black, with light spots and worm-like markings on the back and sides.
- Size class: The largest of the freshwater char.
Lake Trout vs Brook Trout
Tail shape is one of the better field indicators for telling which one you have caught. See the Brook Trout page for its full mark list.
Where it lives
Most lake trout inhabit deep lakes greater than 50 feet, though they can be found at depths well over 200 feet, as well as in deep tributary channels connecting to large lakes. Native to northern North America, from Alaska to Nova Scotia and throughout the Great Lakes.
How to photograph it for identification
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. 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.
Before you keep 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.
FAQ
What does a Lake Trout look like?
Lake trout are distinguished by having a deeply forked tail. The inside of the mouth is white, and the anal fin has 10-11 rays.
How big does a Lake Trout get?
Length is commonly about 17-36 inches (about 43-91 cm); weight is commonly about 3-30 pounds (about 1.4-13.6 kg).
How do I tell a Lake Trout from a Brook Trout?
Tail shape is one of the better field indicators for telling which one you have caught.
Where are Lake Trout found?
Native to northern North America, from Alaska to Nova Scotia and throughout the Great Lakes.
More in North American Fish Identification
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Sources
- dnr.wisconsin.govdnr.wisconsin.gov/sites/default/files/topic/Fishing/Species_laketrout.pdf
- U.S. Fish & Wildlife Servicewww.fws.gov/species/lake-trout-salvelinus-namaycush
- dnr.wisconsin.govdnr.wisconsin.gov/topic/Fishing/lakesuperior/fishID.html
Compiled by the FishLens editorial team
Every fact on this page is taken from the sources listed above; numbers and prices are copied from the source, and prices name the guide or auction and its date. Research and drafting were assisted by AI, and each claim was then checked against the cited sources. Checked 2026-09-10. We do not buy, sell or grade items; the app identifies what you photograph and points you to these references.