The Red Copper John is a popular nymph pattern in fly fishing. It typically features a red or copper-colored wire body, creating a segmented appearance. The thorax is often made with peacock herl, and the fly may have a beadhead for additional weight. The Red Copper John is known for its effectiveness in imitating various aquatic insects, particularly stonefly nymphs. This pattern is widely used for trout fishing and can be productive in a variety of water conditions.