Rainbow Trout vs Brook Trout
The check that settles it
Brook trout has light worm-like markings on a dark back and white leading edges on the lower fins.
Why this matters beyond curiosity
- Look-alike species often carry different limits. Walleye and sauger, black and white crappie, pike and muskie, blue and channel catfish — each pair can have different sizes, seasons and daily limits in the same water.
- Check it before the fish goes in the livewell. Most of the tests on this site take seconds and are far easier on a fish you are still holding.
- If you cannot tell, release it. That is the answer that is never wrong, and it is the one a warden will not argue with.
- Regulations are set by your state or province and change annually. This site identifies fish; it does not tell you the rules. Check the current regulations for the water you are on.
Rainbow Trout
Trout and charOncorhynchus mykiss
- Markings
- spots, horizontal stripe
- Body
- torpedo
- Typical size
- 0.5–6 lb
- Regulations
- Trout waters commonly have separate seasons, stamp requirements, tackle restrictions and daily limits distinct from general fishing regulations.
Brook Trout
Trout and charSalvelinus fontinalis
- Markings
- worm tracks, spots, red orange belly
- Body
- torpedo
- Typical size
- 0.2–3 lb
- Regulations
- Native brook trout populations are declining and many streams have protective limits, gear restrictions or full catch-and-release rules.
Confirming a rainbow trout
- Black spots covering the entire tail, top to bottom.
- Pink or red band along the flank, though this fades on silvery lake fish.
- Spots on a light background, unlike brook trout's light marks on dark.
- Adipose fin present, as on all trout and salmon.
Confirming a brook trout
- Pale worm-like vermiculations across a dark back — light markings on dark, the reverse of trout.
- White leading edge on the pectoral, pelvic and anal fins, backed by a black line.
- Red spots surrounded by blue halos.
- Square tail, giving it the name squaretail.