This fly is my first choice for carp in lakes and ponds. Place it carefully near the head of a feeding (mudding) carp and move it veeeery slowly along the bottom. Try to move the fly into the stirred-up mud right in front of the carp's nose without spooking the carp. (Easier said than done!) If you see the carp flare its lips or turn its head towards the fly or even "wiggle" a little then pick up the slack and see if you feel any resistance. If so, set the hook and hang on -- but not too tight or your leader will pop!
In addition to carp, this fly has also caught numerous largemouth bass, smallmouth bass, panfish and even a trout or two.
I tied this fly following Dble Haul's recipe (see below) using a #6 streamer hook, brown thread, brown maribou for the tail, brown wool yarn for the body, brown hackle and copper wire. Although the wire works very well for securing the hackle, I have had a few come unraveled so I started adding a dab of head cement at the tail end of the body before trimming the tag end of the hackle.