When I began targeting common carp in my local rivers and creeks, I wanted to design a versatile pattern to imitate one of their major food items: crayfish. I was looking for it to be an easy tie with a lot of movement that incorporated some of my favorite materials like schlappen and UV chenille. At the time, I was tying a lot of saltwater patterns for bonefish and permit and I really liked a pattern out of the northeast by Dave Skok called the Diablo Crab. It featured schlappen to create the wide flat body of a crab and the use of those feathers creates a lot of subtle movement on the strip or in any type of current. A very popular carp fly at the time was Mctage's Primordial Carp Stew and I used a few techniques on that fly to round out the fly that became known as the "Carp Crab".
The carp crab resembles a crab but is fished and does a great job of mimicking the profile and movement of a crayfish. When sinking or stripped, the schlappen collapses forming the profile of a darting crawdad. When stopped, the schlappen protrudes outwards and the fly performs a slight headstand resembling a crayfish in the defensive position. The fly is deadly fished on my home rivers of the Delaware and Susquehanna for carp. I've watched carp move over ten feet to take the fly and spin 180 degrees to turn around for second look and eat it. It is commercially available from Catch Fly Fishing and a step by step follows.