Bright red spots are found in lesser numbers along the sides. There are few, if any, spots on the tail in contrast with rainbow, the tails of which are heavily spotted. Unlike brook trout, brown trout have no vermiculations, or wavy lines on their backs and have teeth along the full length of the vomerine bone on the roof of their mouths. Brown-trout coloration is much subdued in hatchery fish, but often assume the brighter colors of wild fish after several months in the stream. Brown trout are also unique in that they are able to change their color quite rapidly as a means of concealment.
Brown trout are also the only fish ever to rest on the stream bottom.
The brown trout has a much wider range than the brook trout, and it's been suggested they can survive in streams that will no longer support brook trout. However, brown trout don't survive well in warm, polluted water either. They can survive for a short period in 81 degree Fahrenheit water, but usually the upper lethal limit for brown trout is about 77 degrees. Brown trout prefer water ranging from 54 to 67 degrees. The main reason for the success of brown trout in streams depleted of brook trout is probably because brown trout are harder to catch.