San Juan Worm Tan - Worm. When fishing waters that require a more exact imitation the Tan San Juan Worm is an ideal fly to go to. Using a more neutral colour it looks more lifelike than the other variations of San Juan Worm making it a necessity for those extremely picky trout that seem to only go for the natural appeal. The Tan San Juan Worm is sure to catch a wide variety of trout including Steelhead, Brook, Rainbow and Brown trout.