The Hi-Viz Gnat is a fishing fly designed to imitate small gnats or midges. It often features a high-visibility indicator on the body, such as a brightly colored post or wing, making it easier for anglers to track the fly on the water's surface. This visibility helps in detecting subtle strikes when fishing for trout in slow-moving or still waters. The rest of the fly typically mimics the appearance of a gnat, with a slender body and fine wings.