To identify salmon, check the inside of the mouth, the spots on the back and tail, and the shape of the tail base. Those three field marks separate Chinook, coho, sockeye, pink, and chum salmon in seconds - this guide (and the chart below) shows you exactly what to look for.
Run them in this order. The mouth alone separates the two species anglers mix up most.
Black mouth with black gums = Chinook. Black mouth with a white gum line = coho. White mouth = sockeye, pink, or chum.
Small spots on the back and the whole tail = Chinook. Upper tail lobe only = coho. Large oval blotches = pink. None distinct = sockeye or chum.
A slender tail base with faint vertical bars = chum. A hump on spawning males = pink. A big-eyed, toothless look = sockeye.
Five Pacific species plus the Atlantic, which sits in a different genus altogether. Sizes are typical adult ranges; individual fish vary widely.
The largest salmon and capable of far more than its typical range. Small irregular spots run across the back and onto both lobes of the tail, over a thick, powerful body. Ocean fish are silvery with a purple-green back; spawners turn olive-brown to maroon.
The Chinook lookalike, and the reason the gum line is worth checking. Spots cover the back but usually stop at the upper lobe of the tail, which is squarish and only lightly forked. Spawning males develop a strong kype and brick-red flanks.
Slim, with a notably toothless look and fine, numerous gill rakers. Bright silver-blue at sea with prominent golden eyes. Spawning fish are unmistakable: crimson bodies under a green head.
The smallest and most numerous Pacific salmon, with very small scales and a thin tail wrist. Spawning males grow the namesake hump. Runs are strongly two-year cyclical, so abundance swings hard between seasons.
A white mouth, a narrow tail base, and silver streaks running through the tail rays. Spawning fish show bold purple-green vertical bars, the calico pattern the species is known for, and males grow large canine-like teeth.
A different genus, native to the North Atlantic. Black X- or Y-shaped spots sit above the lateral line, the tail is almost always spot-free, and the tail wrist is slender. Wild fish are rare in most fisheries; most Atlantic salmon seen today are farm-raised.
Each swatch is split for a reason: the left half is the ocean-bright color, the right half the spawning color. The same fish looks very different in July at sea and in September upriver.
Compare the key field marks side by side. Sizes are typical adult ranges; individual fish vary.
| Species | Mouth & gums | Spots | Tail | Typical size | Other marks |
|---|---|---|---|---|---|
| Chinook (king) | Black mouth, black gums | Small spots on back and both tail lobes | Moderately forked | 10–25 lb+ | Largest species; thick body |
| Coho (silver) | Black mouth, white gum line | Back and upper tail lobe only | Square, lightly forked | 6–12 lb | Wide tail wrist; strong kype when spawning |
| Sockeye (red) | White mouth | None distinct | Slightly forked | 4–8 lb | Prominent eyes; crimson body when spawning |
| Pink (humpy) | White mouth | Large oval blotches on back and tail | Blotched, forked | 3–5 lb | Tiny scales; males hump when spawning |
| Chum (dog) | White mouth | None distinct | Silver streaks in rays; narrow base | 8–15 lb | Calico bars when spawning; large teeth |
| Atlantic | White-gray mouth | X/Y-shaped spots on body, none on tail | Slightly forked, spot-free | 8–12 lb | Different genus; slender tail wrist |
Tip: photograph the open mouth and the tail - those two shots contain almost every mark in this chart.
Salmon and trout share waters and body plans, and steelhead (sea-run rainbow trout) are silver like salmon. The most reliable separator is the anal fin: Pacific salmon have a long anal fin base with roughly 13–19 rays; trout and char have a short one with about 12 or fewer. Add the tail: salmon tails are usually more forked, trout tails squarer. For the full trout side of the story, see our trout identification guide.
The Fish Identifier app reads the same field marks from a clear side photo and suggests the species with the traits it recognized, typical size, habitat, and season. It is a quick second opinion on the bank - and the saved photo lets you re-check the ID at home. For neighboring species, see the freshwater guide and saltwater guide.
Check three marks in order: the inside of the mouth, the spots on the back and tail, and the tail base. A black mouth with black gums points to Chinook; a black mouth with a white gum line points to coho; large oval blotches on the tail point to pink salmon; no spots plus a slender tail base with faint bars points to chum; nearly spotless silver-blue with prominent eyes points to sockeye.
Look inside the mouth. A Chinook (king) has a black mouth including black gums, spots on both lobes of the tail, and a thicker body. A coho (silver) has a black mouth with a white or gray gum line, spots usually only on the upper tail lobe, and a squarer tail. Chinook also grow considerably larger on average.
The anal fin is the classic separator: Pacific salmon have a longer anal fin base with roughly 13 to 19 rays, while trout have a shorter one with about 12 or fewer rays. Salmon also tend to have a more deeply forked tail and a slimmer wrist at the tail base. Steelhead (sea-run rainbow trout) look salmon-like but keep the trout-style short anal fin and a square tail with radiating spots.
When salmon leave the ocean to spawn, hormones transform their bodies: silver flanks turn red, olive, or striped, males grow hooked jaws (kypes) and, in pink salmon, a hump. That is why the same fish can look completely different in July at sea and in September upriver. Identification charts, including ours, therefore show both ocean and spawning phases.
Yes. A clear side photo shows an app the same marks you would check by eye: spot pattern, tail shape, and body proportions. Mouth and gum color can be hard to see in a photo, so for lookalike cases such as Chinook versus coho it helps to photograph the open mouth too and compare the app’s suggested traits with the fish.
Atlantic salmon (Salmo salar) are a different genus from the Pacific species. They show black X- or Y-shaped spots on the body, almost never spots on the tail, and a slimmer tail base. Wild Atlantics are rare in most fisheries; most Atlantic salmon encountered today are farmed fish.
Snap a side profile and let Fish Identifier suggest the species with the field marks behind the match. Save the catch to your collection with location and season.
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Fish Identifier