The Brook Trout is a beautifully-colored fish, iridescent blue to green with yellow spots and sometimes orange to red spots with blue halos across its side. The back may darken to an olive green with dark, wavy, worm-like lines which are lacking in other salmonids. While their undersides lighten to a silvery white, their lower fins are orange with white margins. They have teeth located only in the front of their mouths. Average size of the fish is ten to twelve inches long and one to four pounds, but largest on record was over 14 pounds. The Brook Trout eats a wide variety of insects and small animals. A juvenile will eat insect larva, plankton, and small crustaceans while a larger adult may eat small fish and crayfish.

In the late fall the female will scoop out a shallow hole in the gravel of the streambed or lake bottom around the shoreline. The male and female together then extrude eggs and milt into the hole, the female then covering the fertilized eggs (100 to 5000, depending on her size) to incubate them during the winter. In two or three months the surviving eggs hatch. The young go through a couple of stages before they reach adulthood. During the fry and fingerling stages they eat plankton and as they grow into adulthood they will begin to eat insects and larger prey. The Brook Trout commonly lives its entire life in the same streams and lakes in which it was born or sometimes it may travel out to sea, returning to freshwater to spawn. Maximum life expectancy is about five years old.

Although the Brook Trout is more commonly found at high elevations in the cold water of mountain streams, rivers, lakes and ponds, it populates many watersheds in New England at nearly all elevations. It requires high oxygen content in the water and does not do well in water that gets above 68 degrees in the summer. The Brook Trout is distinguished as being the only trout native to New England waters: brown trout originated from Europe, and rainbow trout came from the northwest United States.