The Black Muddler Fly was created in 1936 by Don Gapen while fishing the world-famous Nipigon River in Ontario, Canada. Today it is the world's leading trout fly, sold in as many countries as there are sporting fish which swim. It's a fly created to represent the sculpin minnow, but imitates a large variety of fish food. Fish feeding on grasshoppers, nymphs, larvae, surface floating flies, sculpins, crawfish and minnows all fall victim to Gapen's creation. It is a fly which can be fished dry, wet, semi-submerged, or kept as a darting minnow.

Selecting muddler size for the fish you seek is best done by using #12, #10 and #8 for insect and larvae life, while bigger hook sizes better represent minnows, crawfish and grasshoppers. Weighted muddlers should be used to represent minnows. They have a body wrapped with lead which sinks the fly instantly, an action that best represents baitfish, such as sculpins down near the bottom.