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.

Over the last few years, I’ve noticed a big uptick in beginner fly anglers. My gauge for this is my inbox. Listeners of my podcasts know that I do my best to answer emailed questions, and a huge ...