Oncorhynchus mykiss

How to identify a rainbow trout

Look for dense small black spots, especially on the back and tail, and a pink-to-red band running along the side. Color varies considerably, so use several features rather than the stripe alone.

Identification checklist

• Numerous small black spots appear on the back, dorsal fin and usually throughout the tail.
• A rosy horizontal band is often visible from the gill cover toward the tail, but it may be faint in young, lake-dwelling or silvery fish.
• The body is streamlined, with an adipose fin between the dorsal fin and tail.
• The inside of the mouth is generally lighter than the black mouth and gum line associated with adult Chinook salmon.
• Steelhead are the same species but follow a migratory life history and are often larger and more silver.

Rainbow trout or salmon?

A pink stripe suggests rainbow trout, but it is not enough by itself. Examine the gum line, distribution of tail spots, anal fin and where the fish was caught. Chinook salmon commonly have black gums and spots on both lobes of the tail. Regulations may distinguish resident rainbow trout from steelhead even when appearance does not.

Photograph it for a better identification

Take a sharp side-view photograph showing the entire fish, then add close views of the tail, mouth and gum line. Keep natural colors intact and avoid filters. Include the general region and whether the catch came from freshwater, an estuary or the ocean.

Habitat and range

Rainbow trout occupy cold streams, rivers and lakes. Steelhead migrate between freshwater and the ocean. Appearance can change with habitat, maturity and spawning condition, which is why a single-color rule is unreliable.