Side by Side

King Salmon Oncorhynchus tshawytscha

Typical: 24–36 in, 10–25 lb

Key field mark: 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 →

Steelhead Oncorhynchus mykiss

Typical: 24–30 in, 5–10 lb

Key field mark: A white mouth AND white gums with spots radiating across the whole tail separate a steelhead from coho (dark mouth, white gums, spots on the upper tail lobe only) and chinook (black mouth and black gums).

• Bright chrome-silver sides, white belly
• Small black spots scattered over the back, dorsal, and entire tail (both lobes)
• Squared tail; 8-12 anal fin rays (fewer than salmon)
• Faint pink-red lateral band (bright on resident/mature fish)
• White mouth and white gums inside
• Small head relative to a same-size Chinook

Full Steelhead guide — season, gear and rules →

When Each Is Running July — current month highlighted

Where King Salmon and Steelhead Overlap

Both run in Great Lakes — that is where telling them apart actually matters.

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