The Clouser Swimming Nymph is an excellent nymph pattern created by the famous Bob Clouser, a smallmouth guide in Pennsylvania. Clouser Swimming Nymph is in excellent trout, bass, and go to carp fly. Depending on size and color they can imitate a multitude of aquatic pray like leeches, soft shell crayfish, small bait fish, tadpoles, and dang near any nymph you can think of. It is also one of the best imitations of damselfly and dragonfly nymphs. Oh yeah a definite must have in the fly box. You can dead drift it by itself or a double dropper setup. You can also treat it like a streamer quarter cast and experiment with your retrieve or just cast out and experiment with your retrieve. If you are fishing for trout 4X to 6X tippet and tapered leader are excellent choices. Or if you are fishing for bigger fish like bass and carp straight line with 10 to 25 lb test.