I'll let you in on a super secret pattern that I developed exclusively for the Denver South Platte. Hell, I even created it's own dubbing blend. A slim bodied Carp Crack tied in DSP Grey dub.
Fish like small crawfish patterns; this particular fly was tied on a Korda Longshank X hook in size 12, but the pattern size is more typical of an O' Shaugnessy style hook in a size 8. Body length, including antennae, is approximately an inch long. Don't discount this fly for it's smaller size though, carp and smallmouth alike will eagerly take this pattern with zeal. Grey is a common color of crawfish found among our many waterways. A UV accent was added to the dubbing blend to give a hint of luster to an otherwise drab colored pattern.
This is quickly becoming one of my go to flies.