How to Identify Trout Species: Rainbow, Brown, Brook, Cutthroat

Trout are among the most popular game fish in North America, but telling species apart can be tricky. Here's a simple guide to identifying the four most common trout species found across Canada and the United States.

Rainbow Trout (Oncorhynchus mykiss)

Range: Native to western North America, introduced across Canada and the US

• Pink to red stripe along the lateral line — the most distinctive feature
• Small black spots on the body, dorsal fin, and tail fin
• White or silver belly with no spots
• Mouth: Inside of the mouth is white
• Size: Typically 30-60 cm (12-24 in), up to 10 kg (22 lb)

Rainbow trout are the most widely stocked trout species in North America. They're found in lakes, rivers, and streams across both Canada and the United States. Steelhead are rainbow trout that migrate to the Great Lakes or ocean and return to spawn — they grow much larger than resident rainbows.

Brown Trout (Salmo trutta)

Range: Native to Europe, introduced and naturalized across Canada and the US

• Large black and red spots on the body, often with pale halos around them
• Square or slightly forked tail with few or no spots
• Golden-brown to olive body with a cream to yellow belly
• Mouth: Extends past the eye on larger fish
• Size: Typically 30-60 cm (12-24 in), up to 15 kg (33 lb)

Brown trout are known for being the most challenging trout to catch — they're wary and selective feeders. They prefer cool, clear streams and rivers but also thrive in lakes. They're found across southern Canada and the northern and western US.

Brook Trout (Salvelinus fontinalis)

Range: Native to eastern North America, introduced across Canada and the western US

• Worm-like marbling (vermiculation) on the back and dorsal fin
• Red spots with blue halos on the sides — like a trout version of a pumpkinseed
• White leading edge on the lower fins, followed by black, then the fin colour
• Square tail fin (brook trout are char, not true trout)
• Size: Typically 20-40 cm (8-16 in), up to 5 kg (11 lb)

Brook trout are the only trout native to much of eastern Canada. They're found in cold, clean streams and lakes across Canada and the northeastern US. They're also widely stocked in mountain lakes in the western US. Brook trout are the most colourful of the trout species, especially during spawning season.

Cutthroat Trout (Oncorhynchus clarkii)

Range: Western North America, from British Columbia to California and east to Alberta

• Red, orange, or yellow slash under the lower jaw — the defining feature (the "cutthroat" mark)
• Small black spots concentrated toward the tail
• Body colour: Olive-green to bronze, often with a reddish or golden tint
• Mouth: Inside of the mouth is white (like rainbow)
• Size: Typically 25-50 cm (10-20 in), up to 5 kg (11 lb)

Cutthroat trout are native to the western US and Canada. There are several subspecies, including the coastal cutthroat, westslope cutthroat, and Yellowstone cutthroat. They're found in cold, clear streams and lakes. Some populations are threatened or endangered, so check local regulations before targeting them.

Quick Identification Table

Key features to look for:

• Pink stripe on the side = Rainbow trout (or steelhead)
• Red spots with blue halos = Brook trout
• Large spots with pale halos = Brown trout
• Red slash under the jaw = Cutthroat trout
• Worm-like markings on the back = Brook trout
• White mouth inside = Rainbow or cutthroat

Trout Fishing Tips

• Match the hatch — Trout feed on insects, so matching local insect hatches with your fly or lure selection is key.
• Fish early and late — Trout feed most actively during low-light periods, especially in summer when water temperatures are high.
• Use light line — Trout in clear streams are easily spooked. Use 4-6 lb test fluorocarbon leaders.
• Identify your catch — The CatchTales app includes a full fish identification guide for 305 species, including all trout species found in Canada and the US.

Published July 2026 by the CatchTales team.