Rinse fish thoroughly in cold water; pat dry. Dredge fish in flour; shake off excess flour.
Sauté fish in 3 tablespoons butter in a large skillet over medium heat until golden brown, turning once. Drain fish well on paper towels, and transfer to a warm serving platter. Garnish with lemon slices, if desired.
Note: Sautéed Trout is delicious as a breakfast dish.