The best crawfish pattern I’ve ever fished. Tied on a twenty six degree jig hook to keep it riding straight up and down with a small bead at the jig for a little extra weight. I tie the head using legs, flash, shrimp eyes and dubbing to create a realistic look from behind. I use hackle to add a defined shape to the claws while keeping them from looking too big and scaring the fish away. The body is built out of Spawn Simi Seal to create a realistic body, while also giving the flies body a bit more free movement in the water. 
 
I have fished this fly on a two fly rig multiple times with a flashier, more attractive fly in front, and the Carl in the back with much success. Once I fished a variation on a wooly bugger  in the front with one of these suckers in the back and caught twenty bass in one hour. If you do decide to run two bass flies I would definitely recommend fishing the size two on an seven or eight weight with floating line. (I really like the TFO Axiom Two X)