The Holschlag Hackle Fly (HHF) was created for smallmouth bass for which it’s originator has used it with great success since the 1990s.
How to fish:
The HHF should be hopped along the bottom with a pull and pause retrieve. This is aided by fishing the fly under a strike indicator and by using a level leader.
Smallmouth Fly Fishing, The Best Techniques, Flies, and Destinations, 2006, Tim Holschlag, ISBN 0976387603. Preview here. Supernormal Stimuli.
Tim Holschlag, on Super Sized Smallmouth.