In theory, fly-fishing is a simple sport: Pick a body of water, choose a fly-fishing rod, select your “fly” (or bait), tie a secure knot, cast your line and, hopefully, land a fish on the other end.

Fly fishing is synonymous with trout. When most people think about fly fishing, they conjure images of mountain streams and fish sipping mayflies and caddisflies off the surface. It’s true that the ...