When it comes to fly fishing for trout, your go-to setup is the nymph rig. Why? Well, it's commonly known that 80- to 90-percent of a trout's diet is subsurface making wet flies, weighted flies and sinking flies to be some of the most productive patterns. Whether your new to fly fishing or need a better understanding of the nymph, I hope this how-to helps!
For starters, most applications will call for a standard 9-foot leader, strike indicator, shot and of course flies. Starting a double nymph rig, begin with the leader and attach it to you floating fly line. A pre-looped leader connected to a pre-looped fly line with a loop-to-loop connection is quick and easy.
Next, add a lead or top fly to your setup by tying on the larger of the two flies you have picked out for a nymph rig. Attach it to the leader or if condition call for a longer leader, add more tippet material to the end of the leader. For easy instruction, start with the basic 9 footer and add a lead fly such as a stonefly or bigger nymph like a Prince or pheasant tail.
This is a double nymph rig, so now comes the adding of the second fly. Take about 18 inches of tippet material and tie one end to the bend of the lead fly. Some anglers like to leave a long tag on the lead fly and tie off to that. Still, others even tie a dropper loop, but to keep things easy here, stick with tying the tippet to the bend of the first fly.
Next, take your equal or smaller-sized fly and tie it to the other end of the tippet. Now you have two flies ranging from 8- to 18- inches apart. Personal preferences and on the water knowledge will eventually help you decide the distance but as a general rule, 8- to 14- inches is best.
The hardest part of this rig is determined by the water you are fishing. Setting the indicator or what mainstream anglers call a "bobber" and attaching the weight or shot to the line is the most technical part. If the water is deep and fast, then a piece of larger shot will be needed to help you keep in contact or near the bottom when fishing. Shallower and slower water will not require as much weight on the line as sometimes weighed flies are enough.
As for the strike indicator, you have a lot of options. I like yarn with a dental-sized, tiny rubber band or a Screwball indicator. Some folks like foam or thingmabobbers as well. Anglers should set the level of the strike indicators to match the water as well. If you are fishing in a swift, 3-foot deep run, than you should give your flies enough slack to reach the bottom. The general rule is about 1.5 to 2 times the depth. So if you are fishing 3 feet of water, set the indicator at 6 feet, so six feet of line will sink. Always give yourself plenty of depth and you should get caught on the bottom on occasion. See photos for step by step ideas.