Side by Side

Coho Salmon Oncorhynchus kisutch

Typical: 20–26 in, 4–8 lb

Key field mark: Coho has a WHITE gum line (the reliable tell) with tail spots on the upper lobe only; Chinook has a black mouth WITH black gums and spots on both tail lobes; steelhead has a fully white mouth and gums.

• Chrome silver with a metallic blue-green back
• Black spots on the back and the UPPER lobe of the tail only
• Dark/gray mouth interior but a WHITE gum line at the tooth bases
• 12-15 anal fin rays
• Broad, only slightly forked tail
• Typically smaller and slimmer than a Chinook

Full Coho Salmon guide — season, gear and rules →

King Salmon Oncorhynchus tshawytscha

Typical: 24–36 in, 10–25 lb

Quickest tell: Spots across BOTH tail lobes plus a solid black gum line (the "blackmouth") confirm King/Chinook over Coho, which shares a dark mouth but has WHITE gums and spots only on the upper tail lobe. (An adipose fin alone proves nothing, every salmonid has one.)

• Black gum line at the base of the teeth ("blackmouth"), inside of mouth dark
• Black spots on the back AND on BOTH lobes of the tail
• Silver body with greenish-blue back, small scales, silver retained on the tail
• Robust, deep body with a broad, firm tail that holds its shape when gripped
• Anal fin shorter-based than a trout's; large sharp teeth

Full King Salmon guide — season, gear and rules →

When Each Is Running July — current month highlighted

Where Coho Salmon and King Salmon Overlap

Both run in Alaska — Southcentral & Southeast, Great Lakes, Pacific Northwest — that is where telling them apart actually matters.

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