How and Why to Fish A Two-Fly Nymph Rig

This article was originally titled "Doubling Down" in the Feb-Mar 2016 issue of Fly Fisherman magazine. 

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If you play blackjack, you are familiar with the idea of "doubling down." It is a smart, high-reward strategy that allows players to double their bets in exchange for just one additional card.

I use a similar philosophy when I'm on a river. For a professional guide, the stakes are high when a customer pays for a good day on the water. Failure is not an option, so my game plan on any watershed is always to use two flies whether I'm nymphing, dry-fly fishing, or using streamers. This strategy mathematically increases my odds, but you've got to have the right combination of flies and presentations to go along with it otherwise you're not looking at a dependable bet.

After 25 years of guiding, I'm convinced there are endless possibilities for two flies tandem nymphs, double drys, a dry and a nymph (or emerger), double streamers, or a streamer and a nymph all of which are effective under a wide range of conditions. The best advice that I can give you is to avoid a standard approach such as a San Juan Worm with an RS2 for all water conditions. There is no good one-size-fits-all strategy.

Customize your tandem rigs based on the conditions evolving in front of you. Carefully analyze the water clarity, depth, speed, temperature, look for any evident hatches, and so on, before you choose your flies.

Seeing Double: Two-Fly Nymph Rig

I grew up fishing famous Western tailwaters like the South Platte, Blue, and the Fryingpan all rivers known for their exceptional dry-fly fishing.

My father introduced me to the concept of fishing tandem dry flies when I was a boy on the Taylor River near Almont, Colorado. The Taylor is notorious for its reliable mayfly hatches and superb attractor dry fishing during the latter part of the summer, and it quickly became apparent that fishing with two dry flies (in comparison to one) elevated my dry-fly results to a new level. Whether I was trying to pound fish up with attractors, or using exact imitations during the height of a hatch, double drys gave me the upper hand in fooling selective trout.

When there are no evident hatches, fishing with a large attractor such as a Royal Wulff, Lime Aid, Renegade, H&L Variant, or a hopper-type pattern followed by a size 20 Parachute Adams or Blue Dun is a good idea. A large, beefy dry fly is an effective method to search the river, looking for opportunistic surface feeders holding in shallow riffles, transitional zones, pockets, glassy pools, or along the edges.

After spring runoff subsides, trout eat large dry flies with confidence, but as the season progresses, they become more educated, and the small trailing fly becomes more important.

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The smaller (#18-22) fly should be more imitative of the aquatic insect hatches of the season, or else a small terrestrial like a beetle or ant. It's not uncommon for a trout to see the attractor, rise toward it, reject it, and take the smaller fly at the last second. A trout may not come all the way to the surface just to eat a small ant or Trico but if it's already there, why not?

The attractor/indicator fly helps you locate and follow your smaller fly, especially in riffled currents, or foam lines. This is especially helpful in situations like a Trico spinner fall. Even in the best conditions, it's hard to see a size 24 spent spinner on the water.

If the fish are spooky, your attractor/indicator fly might be something like a size 18 Hi-Vis Baetis. Everything is relative. A size 18 is much easier to see than a size 24 and if you plop a size 10 grasshopper in a pod of rising trout, they'll likely scatter, so downsize your indicator fly when necessary.

If you see a trout rise anywhere near the indicator fly, or it abruptly sinks, assume a trout took the smaller fly and set the hook.

During the height of a Blue-winged Olive, Pale Morning Dun, Green Drake, or Red Quill hatch, fishing with two imitative dry flies doubles your chances of success, so I skip the attractor element altogether.

Even when you ditch the attractor fly, you can still give the fish two different looks by using one Catskill-type dry along with a low-riding pattern like a parachute, No-Hackle, or Compara-dun version of whatever is hatching. This provides two different silhouettes for the fish to analyze when they become extremely finicky during the peak of a hatch.

Most of the time, trout take the fly that sits flush in the film because it provides a much more realistic impression, but I get enough strikes on a conventional hackled fly to warrant keeping it on.

A few years back, my dad and I were fishing during a Green Drake hatch on the Taylor River. We were both using a size 12 Quill Gordon and size 12 Mathews's Sparkle Dun as a trailing fly.

It was drizzling, and the Green Drakes were having difficulty getting off the water while about two dozen trout feasted in a tailout just above Almont. To our surprise, the Quill Gordon (a conventional hackled fly) outfished the Sparkle Dun by a 3-to-1 margin.

It must have had something to do with the newly hatched duns skittering on the surface trying to dry their wings out. The rain was clearly stalling the emergence in comparison to a bright and sunny day where the duns leave the water quickly.

My guess was the hackle provided some lifelike movement that simulated the behavior of the Green Drakes trying to get off the water. Sometimes imitating the behavior of the naturals is as important as choosing the fly itself. That experience shows that using two flies can teach you things you might not discover if you're just using one fly or the other.

Gearing up. A 9- to 12-foot 4X tapered leader is versatile for most dry-fly situations. Simply add tippet to lengthen the leader.

I use nylon monofilament because it floats better and is more flexible than fluorocarbon, and both attributes help encourage drag-free drifts.

The first fly you tie to your tippet is also called the point fly. The second smaller fly is called the dropper, the trailer, or the trailing fly. I tie my dry-fly droppers off the hook bend of the point fly using 12 to 24 inches of tippet.

One tough part of fishing with two dry flies is preventing micro drag that can lead to refusals. If the two flies are in substantially different currents, one can pull on the other causing both flies to drag. Sometimes the easiest fix is to shorten the length of the tippet material between your flies. In most cases, this small adjustment keeps your flies closer together, and likely in the same current speed. A better but technically more challenging situation is to use a longer and thinner tippet section between the flies, and use a pile cast or parachute cast to create plenty of slack between the flies. 

Dynamic Fly Duo

Die-hard streamer junkies know that two streamers are almost always better than one, but it's not simply a matter of having two hooks in the water.

Use streamers with different sizes and colors to imitate a wide array of forage items including minnows, baby trout, leeches, sculpins, and crayfish. As a general rule, the point fly should be the larger and heavier of the two streamers.

A white, tan, or cream-colored streamer with a dash of flash is an excellent attractor (point fly) that grabs attention and draws trout out of their lairs, but a subtle more imitative pattern usually gets the hookup.

I have many times watched trout move several feet from undercut banks, logs, submerged boulders, and other structure to chase my attractor streamers such as #8-10 Crystal Buggers, #2-6 Lunch Moneys, and #2 Meat Whistles.

Using a white or other light-colored streamer as an attractor helps you locate your flies and anticipate strikes. Trout frequently grab the streamer between strips on the pause and you often can't feel these strikes at all. If you can see it happening though, it's a different ball game.

Just be sure that the visual anticipation doesn't cause you to pull the fly away from the trout prematurely. Make sure the trout has it, then strip-set to make the connection. Don't lift the rod to set the hook as you risk pulling the fly completely out of the trout's field of vision. (Read Oliver White's account of using an white-and-olive Dalai Lama for visual streamer fishing on the Zhupanova River.)

While I get a fair number of quick, reactionary strikes with a big, light-colored attractor, I catch the majority of my trout on the trailing fly such as a #10 gray pine squirrel leech or a black or brown goat leech, because it's smaller and moves more naturally in the current. The convincing strikes on the trailing fly are also partly due to the fact that the action of the point fly is restricted because it is attached to the dropper fly.

It's no secret that streamers tend to fish best in low light at dawn or dusk, and also during the shoulder seasons when trout become easily aggravated near the spawning season. These windows of opportunity routinely produce some of the largest trout of the year.

Gearing up. Trout are not leader shy when they focus on streamers, and you need heavy leaders to throw big meals, so I typically use short monofilament leaders terminating in 2X tippet. This helps you cast two heavily weighted streamers, even in windy conditions. Short, stout leaders also reduce break-offs from snags, overhanging brush, and other streamside obstacles and help you land trout quickly for a successful release.

I tie on the point fly with a clinch knot. I attach the dropper monofilament to the hook bend using another clinch knot, and then tie on the final fly using a no-slip loop knot.

This knot allows the dropper fly to move freely in the current in comparison to any kind of a clinch knot. This loop knot first became popular in saltwater fly fishing, and is useful whenever you use heavy tippet, and still want maximum movement from your fly. (Learn to tie Lefty's no-slip mono loop knot.)

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Pat Dorsey has been a fly-fishing guide for 23 years and is a Fly Fisherman field editor. He is the author of Fly Fishing Tailwaters (2009), Tying and Fishing Tailwater Flies (2010), and most recently Colorado Guide Flies: Patterns, Rigs, & Advice from the State's Best Anglers & Guides (Headwater Books and Stackpole Books, 2015).