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.

If you’ve been in central Pennsylvania during the warmer months, it’s not uncommon to find a fisher wading in the water, whizzing their line around in the air, then plopping it into one of the many ...