Nymphing: How to read a fly fishing indicator — What you might be missing

by | Oct 17, 2018 | 17 comments

I know, I know. You don’t like to fish with indicators, right? You think an indy removes the angler from contact with the nymphs. You believe a fly fishing indicator actually gets in the way of strike detection more than it helps the situation. Granted, there are big problems with the way most fly fishermen use indicators. And I know a lot of anglers who refuse to attach them to a leader.

But I also know many more good anglers who see the value of indicators, who reach for an indy (or a dry-dropper rig) when a tight line nymphing presentation fails, who recognize that an indicator is an amazing and useful tool that extends our effective nymphing range, balances out a drift and helps keep the flies in one current seam.

I think a lot of anglers miss the finer points of the indy game. Good indicator nymphing (or dry-dropper fishing) is not just a chuck it and chance it affair. Instead, careful attention to the indy itself, reading the water against the position and behavior of the indicator, is a necessary skill if the tactic is to be productive.

A fly fishing indicator is both a suspender of weight and an indicator of the drift.

Let’s dig in . . .

READ: Troutbitten | It’s a Suspender, not just an Indicator


Get tight first

All of this is predicated on the indy being in touch with the nymphs. And that happens at various points following the cast: sometimes sooner, sometimes later.

One of the great things about indy fishing is how effectively a slight amount of slack in the system can be managed. A tight line presentation tends to pull out any built in, useful slack, while an indy rig may maintain a bit of slack between the flies and the indicator for long stretches within a drift.

All of the subtleties discussed below, however, occur once the indy is in touch with the flies (or the weight) under the surface.

READ: Troutbitten | One Great Nymphing Trick


In touch yet?

A good indicator sends a signal to the angler once it gains contact with the nymphs.

Ideally, we land the nymphs upstream of the indy, all in one current seam. As the nymphs sink and drift downstream, they eventually gain contact with the indicator floating on the surface. (Skilled anglers manipulate the available slack between the nymphs and the indy as the pair hit the water.)

When the two are out of touch, the indicator may orient sideways a bit. It may canter off to the side. It may appear unstable, rocking and swaying with the currents. Watch the indy for all of that.

And then watch for it to change. See the indy tighten up a bit. See its orientation shift. Watch how it stands upright. All of this happens once it gains contact with the nymphs underneath. This is how you know the indy is in touch with the flies.

Importantly, gaining contact is different than slowing down. That’s the next thing to watch for . . .

READ: Troutbitten | Tight Line vs Indicator


The lag

“How do I know if my nymphs are on the bottom?” It’s a question considered by every fly fisher who’s ever probed the depths of a river. The better question to ask is, “Are my nymphs in the strike zone?”

The indicator signals the position of the nymphs to the angler. And when the nymphs are in the strike zone, the indy slows.

READ: Troutbitten | Forget the Bottom | Glide Nymphs Through the Strike Zone

Watch the surface currents. See the bubbles. Even without foam or bubbles on the surface, you can see the speed of the topwater if you look close enough.

When the indy first lands, it’s carried only by the influence of the surface currents. First, watch for the indy to gain contact with the nymphs — watch its orientation or stability, as described above. Next, watch for the indicator to lag behind the surface currents. See it drift slower than the top water. This is your indication that the nymphs are near the bottom.

Water flowing near the riverbed flows slower than the surface currents. It’s an elementary fact that should be printed on the back of every little plastic package of indicators. The water at the bottom of the river is slowed by the rocks, tree parts, weeds, etc. Trout live there. They sit on the bottom, conserving energy, while faster water flows above them. Get your nymphs down into this strike zone and catch fish.

And when the indy drifts slower than the top current, it’s a signal that the nymphs are where they should be.


Do you see it now?

We all watch the indy for a strike. That’s the obvious indication from our “strike indicators.” And I’ll leave it to you to decide whether to set on every jiggle, or only the major bumps of the indicator. Most of those jiggles and bumps are not trout takes, but we set anyway, because one out of twenty times . . .

READ: Troutbitten | Nymphing: Set on Anything Unusual

Does your fishing buddy who doubles up your fish count have a sixth sense for nymphing that you don’t?

Probably not.

Here’s the thing: by watching the other signals of the indy, by observing the orientation and stability, and by watching for the slow down, the best nymph fishermen gather more data about the drift than the guys who just chuck it and chance it. The skilled nympher processes all that data in real time. He factors in the positioning and the contact of the nymphs against the indicator. And he weighs all of that against the probability that each of those small jiggles or bumps is a strike. That is the sixth sense stuff.

READ: Troutbitten | Tight Line Nymphing with an Indicator — A Mono Rig Variant


Photo from Matt Grobe

What Indy?

I know enough good anglers to understand that indicators are a personal choice, and a skilled nymph fisher can make just about any indicator style work for him.

So fish what you like, but choose wisely. Select your indicator with the above properties in mind.

All indys will show you the slow down. But some don’t indicate the orientation very well — they don’t indicate contact with the nymphs.

I fish Dorsey yarn indicators and Thingamabobbers, and when I fish indys, it’s most often with a tight-line-to-the-indicator style on a Mono Rig.

READ: Troutbitten | The Dorsey Yarn Indicator — Everything you need to know and a little more

I love the Dorsey as a first choice because of how well it indicates everything discussed above. It’s extremely sensitive because it’s so light. Even better, the varied angles at the tips of the yarn show me a lot more about a drift than most other indy styles. The Dorsey usually canters to the side or lays down a bit when it’s out of touch with the weight underneath. Then it perks up and sits tall on the surface once it feels the payload. What’s more, by using two colors in the Dorsey, I see slight rotations and minor twists as the Dorsey floats on the surface. Those motions provide an angler with a full picture of what’s going on with the flies underneath the water.

My own second choice of indicator is a Thingamabobber. I like it for casting at distance, and I like it for extra long drifts that I plan to finish out all the way below my position (down and across). The Thingamabobber doesn’t send nearly as many subtle signals as the Dorsey, but it has its own set of strengths.

The Troutbitten slide-able Thingamabobber hack

READ: Troutbitten | Your Indicator is too Big

Last thing here: Whatever you choose, go with lighter and smaller indicators, because they are more sensitive. Less built-in buoyancy means a more reactive indicator — and you can better read the subtle signs. Use indys that are on the edge of sinking under the payload. Adjust often. Watch closely.

. . . and fish hard.


Enjoy the day.
Domenick Swentosky



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Domenick Swentosky

Central Pennsylvania

Hi. I’m a father of two young boys, a husband, author, fly fishing guide and a musician. I fish for wild brown trout in the cool limestone waters of Central Pennsylvania year round. This is my home, and I love it. Friends. Family. And the river.

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  1. Good points! If one really wants to see how the indicator can convey what the flies are doing I would recommend getting a 4 gram Blackbird Phantom float and drift it a few times. Because of their length and being rigged in-line they will exaggerate all the movements you mentioned.

    • Yowsa! Those are huge, budy. So, anything that heavy and with that much buoyancy won’t react very well to the relatively light pull of a pair of nymphs — not the nymphs we use, anyway. I’m familiar with those floats, but the Dorsey, for example, will show you the same thing at a fraction of the weight and be much more sensitive. Those are my thoughts.

  2. I think i am moving away from the thingamabobber and moving towards the air lock ones or the New Zealand type. I would also be interested in the mentioned thingamabobber hack in your last pic.

    • Hi Jason. I’ll post the TB hack someday. It uses the same attachment system as the Dorsey and allows for the TB to slide up and down a piece of tippet very easily.

      • Good. I’d like to see that hack also.

  3. Great post, Dom: a graduate level course in nymphing with an indy.

    As you say, the choice of indy is quite personal. I fish with both Dorsey and Thingamabobber indies, but I especially like balloon indies because they give me so much information. For example, a balloon indy that is somewhat oblong will lie on its side as the nymphs are sinking and then perk up when they first hit bottom. Then it will record the nymph’s journey on the stream bottom with a series of very telling bumps and jerks.

    I struggled with balloon indicators until I came up with a way of attaching them that is simple, and allows for easy adjustment up and down the leader. Find an old ballpoint pen and remove the plastic cylinder that used to hold the ink. Cut it into little pieces, around 3/8″. When you want to attach a balloon, double your leader and stick it through on of the cylinders. You now have a loop on the other side of the cylinder. Now, put a small, cheap water balloon through the cylinder (how far determines how large the indicator is), blow into the balloon a little (just enough to inflate it tiny bit), and then pull the leader plus balloon back into the plastic cylinder (you can see the balloon through the clear cylinder) and cut off the tag end of the balloon. The resulting indy will not kink the leader, will slide up and down the leader easily, and the balloon won’t lose air for a couple of days.


    • Thanks for this suggestion, Alex. I’m going to give this a try. I’ll be fishing out west next summer, and balloons can be especially good on some of the big rivers.

  4. Now, for a question. Everyone has to start somewhere. When you start a day of nymphing on a medium sized stream, do you tend to begin with or without an indy, and why?


    • I prefer to tight line nymph. So I usually start with water that lends itself to the technique.

  5. WOW !!! Great info Dominick I just read it a couple of times

  6. Thanks Dom. Since reading this https://troutbitten.com/2015/09/13/fishing-with-the-dorsey-yarn-indicator/ and your other writings the Dorsey has become an integral part of my approach to the river. It’s the inherent versatility and speed in which it allows an angler to adapt to the water that makes it so effective for me. From the more usual applications to the less usual like using a micro Dorsey to better control the tippet’s entry into the water when sight fishing.
    With neon wax to form different functioning in-line indicators, Dorsey and a dry fly I find one long-leader covers all my trout and grayling fishing.

    The only real downside being that the Dorsey isn’t particularly aerodynamic which can cause some issues when fishing with a very light leader but I think I found a solution to that in Daniel’s latest book.

    • Very nice, Justin. What is the solution in GD’s book? My solution is to keep the Dorsey small.

      • I try and keep them small too, with a ballenced rig that does solve most problems. I’ll often fish a Dorsey too small to suspend the nymph(s) but my two go to leaders for 99% of my trout fishing are made from fairly stiff flurocarbon weighting 0.4g per 12ft (the same as 12lbs maxima) or 0.36 per 12ft so every little helps.

        On page 79 GD talks about wanting the wool to look like the “head of a troll”. When I’m prepping the Dorseys at the tying table I trim some so when folded double they form more of a symmetrical airfoil shape/troll head.

  7. Do you have an article or video on the slide-able thingamabobber hack? I couldn’t find anything in a search
    Thanks, Jimmy H


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Domenick Swentosky

Central Pennsylvania

Hi. I’m a father of two young boys, a husband, author, fly fishing guide and a musician. I fish for wild brown trout in the cool limestone waters of Central Pennsylvania year round. This is my home, and I love it. Friends. Family. And the river.

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