The most obvious identifying characteristic on the rainbow trout--the rosy band running
horizontally down the fish's side--is rarely visible on individuals found in the Great
Lakes. Lake-run rainbow trouts, called steelheads, tend to be entirely silver or
bluish-silver. Spawning or recently spawned fish may be quite dark. Breeding males have an
extended, hooked jaw.
The best way to identify the Great Lakes rainbow trout is the spotting--the tail and
adipose fins are distinctly and profusely spotted in black or brown. However, rainbow
trouts do not have the reddish spots shown by the brook and brown trouts.
Look for:
- brown or black spots (not red), especially profuse on the tail and adipose fins.
- Caudal fin broad but not long, moderately forked
- 8-12 principal rays in caudal fin
- lateral line with 100-150 pored scales
Complete rainbow trout
profile.
Main trouts and salmons page.
Sources: "Fishes of Isle Royale," by K.F. Lagler and C. R.
Goldman, Isle Royale Natural History Association, 1982.
Fishes of Wisconsin, by George C. Becker, University of Wisconsin
Press, 1983.
Freshwater Fishes of Canada, by W.B. Scott and E.J. Crossman, Fisheries Research
Board of Canada, 1973.
