Brook trout, the state fish of Michigan, breed in the fall and spawn in October and November. The female brook trout find riffle areas that have gravel bottoms in spring fed streams. Brook trout also look for spring seepage pond areas and lake shores with fast currents. They can readily be found spawning in lake bottoms where the groundwater seepage favors spawning.
Sac fry stay in the redd spawning bed until the yolk sac of each is absorbed, and then, at about 1 1/2 inches, they swim away to feed. They need 2 to 3 years to mature and normally do not live longer than 6 years. The brook trout that lives in streams can easily reach between 7 9 inches, while Great Lake brook trout, called coasters, can get up to 25 inches long and weigh 10 pounds.
Before the brook trout mates in the fall, the male becomes even more colorful than normal, turning into a bright orange and red color especially along their sides. Otherwise the brook trout is a long fish with large mouth extending past its eye and variations in color along the body. They can be olive, blue, gray or black with silver belly and squiggly markings along the back. The tail is square and very rarely can be forked. Brook trout usually have red spots inside blue halo markings.
It is highly prized as a sport fish and also for eating. Many baits lure brook trout.