Browns grow nearly one inch per month during mid-summer, with much slower growth in spring and fall, and like most fish, usually no growth occurs during winter. A l0-inch brown trout stocked from an Iowa hatchery is probably about 18 months old. Trophy-sized fish over 3 pounds have probably survived in our streams for at least 3 years. Brown trout strongly orient to hiding cover at the first sign of bank movement, be it fishermen or a fish-eating bird. They seem capable of survival in a variety of coldwater streams as long as there is ample protective cover and water temperature does not continuously exceed 70 degrees F. Brown trout feed largely on terrestrial and aquatic insects, worms and small crayfish.
Fish become important in the diet of larger browns.
Daily feeding patterns change seasonally with varying water temperature and light intensity. Peak insect drifts will often occur after dark, and browns are well-known for their nocturnal feeding. Brown trout are very capable of switching from life in a hatchery to that in a stream environment and adapt readily to a diet of natural food items. Brown trout will remain our most important fish for fingerling stocking and for our special regulation trout streams due primarily to their ability to survive well under different stream conditions. They are probably the most tedious species of trout for the average angler to catch, but as a result they provide the greatest challenge to dedicated trout fishermen.