Fly Fishing 101

How to Use Strike Indicators for Fly Fishing: Types, Depth and Reading the Take

Daniel Bowman Updated November 4, 2026 10 min read

If you fish nymphs, flies that drift underwater, you usually can't see the fly or the fish. A strike indicator solves that. It rides on the surface, you watch it, and when it does something unusual, you set the hook.

This guide covers what an indicator actually tells you, the main types and how each one attaches, how to size it and set its depth, how to read a take, how to mend without ruining the drift, and what Georgia's published rules say. On Noontootla Creek, "95% of our fish here still come on nymphs like pheasant tails or a pat's rubber legs." If you'd rather fish with a guide, flies, leaders and tippet are provided, and our trip finder can match you to a river.

What does a strike indicator tell you?

Two things: when a fish takes your fly, and how your fly is drifting. The Orvis Learning Center's lesson on what an indicator is puts the second point first: "your indicator much more than being just a signal of a strike is a drift indicator. It tells you in what current lane your fly is drifting."

Orvis's lesson on detecting strikes explains how to use it that way: "if it begins to struggle against the current, you know the fly is dragging and that you need to mend line. If you watch your indicator, and make sure that it's traveling at the same speed as the bubbles or debris in the current, you can be pretty sure you're getting a drag-free drift."

If the indicator moves faster or slower than the bubbles beside it, the fly is dragging, and a mend helps.

What are the main types of strike indicator?

Several, and they attach differently. From the Orvis lesson on types of indicators:

Putty is another option, not in that lesson: Loon's Biostrike "can be rolled in a ball with wet fingers and applied anywhere on a leader, then removed and placed back in the container."

Orvis adds that the Airlock "doesn't put a kink in your leader," and that stick-on foam ends up "all over the riverbank because they come off and they never disintegrate."

Which type should you use on which water?

Match the indicator to the water and the fish:

• Fast, broken water: an air-filled plastic indicator like a Thingamabobber, which Orvis says floats "really, really well" and its product page says "never sinks."
• Slow, flat or clear water: yarn. The Orvis yarn lesson says "the yarn is much easier to cast, it's less air resistant, it lands a lot lighter on the water. And also yarn indicators are so much more sensitive than the hard plastic ones."
• Changing depths through the day: putty, which you can remove and re-roll in a new spot, or yarn, which you can re-set on the leader.

If your yarn starts to sink, the same yarn lesson suggests a couple of false casts to dry it, or a dip in dry-fly powder, after which it "will float high for another hour or two."

How big should a strike indicator be?

As small as you can get away with. Orvis's lesson on sizes and colors says "you always want to try to use as small an indicator as you can get away with," because a big one "makes a big splat" and "is probably going to spook the fish."

The rule is simple: "big enough to float the flies, but not so big it's going to make a big splat." And the fix if it's too small: "If you can't see your indicator, or if it sinks right away, switch to a bigger one."

On color, the same lesson notes that "in heavily-fished areas, sometimes fish are frightened or suspicious of brightly-colored indicators," and suggests clear or white there. On public water near a road, that's worth trying.

The New Zealand Strike Indicator Co. gives a color guide for its yarn that matches the light you're fishing in:

• Bright orange: "when sighting is a challenge."
• Black: "when there's a glare and the water surface turns silver/gray."
• Chartreuse: "best when the background is dark or in low-light conditions."
• White: "looks like an air bubble," which fits the clear-or-white advice above.

How deep should you set the indicator?

Start at about one and a half to two times the water depth, then adjust. Orvis's depth lesson says to "set your indicator about one and a half to two times the water depth above your first fly or weight."

The reason for setting it deeper than the water, as the lesson explains: "in fast water, the indicator is on the surface where the water is faster, but trout are closer to the bottom where the current is slower. So your fly drifts at an angle to the indicator." In slow water, the lesson says you "might need to set your indicator at just about the water depth, especially with heavier flies."

Then check it on the water:

1. Start with the rule for the depth of the run.
2. Watch the indicator. Orvis says you should see it ticking or stuttering along the bottom about every half dozen drifts.
3. Not ticking bottom about every half dozen drifts? Move the indicator 3 to 6 inches up the leader, toward the rod tip.
4. Hanging up every two or three casts? Move it a few inches down the leader, closer to the fly.
5. Reset at every new spot, since depth changes from run to run.

Our nymphing guide for beginners walks through the full rig, including weight.

What does a take look like?

It depends on the water speed. Orvis's lesson on recognizing strikes says "the faster the water, the harder the take," and that "the indicator will sometimes even plunge underwater just like a real bobber. In slower water, the take might be more subtle and could be just a minor hesitation."

Signs to set on:

• The indicator goes under.
• It stops or hesitates while the bubbles beside it keep moving.
• It does anything that doesn't match the current around it.

The same lesson's advice is the best rule for a beginner: "hook sets are free." If something looks different, set. Our guide to setting the hook covers how.

How do you mend without moving the indicator?

Lift and flip the line, not the float. Orvis's nymph mending lesson says to "mend enough that you go all the way to the indicator but without moving it. Moving the indicator moves the flies as well."

Which direction: "If the water next to you is faster than the water your flies are drifting in, mend upstream"; if it's slower, "mend downstream." And the reason it matters: "90% of the time, dead drift is the way to go," meaning a drift with no drag.

Our guide to mending fly line covers the technique in more detail.

Can a dry fly be your indicator?

Yes. That's the dry-dropper rig: a buoyant dry fly on top, with a nymph hanging under it on a short piece of tippet. Orvis's dry-dropper lesson uses a dropper "anywhere from six to 20 inches can be longer" and notes "you're not trying to scratch bottom when you're fishing a dry dropper. You want it to hang in mid-water."

The take is easy to read: "anytime your dry even begins to sink, you need to set the hook." Our dry-dropper guide shows how to tie it.

When the water is too deep or fast for a dry-dropper, a dedicated indicator takes over. And when you want to skip the float entirely, there's Euro nymphing; our comparison of Euro and indicator nymphing covers that choice.

How do you rig an indicator, step by step?

The basic indicator rig, using the Orvis lessons above and its rig setup lesson:

1. Tie on the nymph at the end of your tippet.
2. Add weight if you need it, a beadhead fly or split shot above the fly, to get down to the fish.
3. Attach the indicator up the leader, at the starting depth from the rule above.
4. Cast upstream of where you think fish are holding.
5. Mend right away so the flies can sink without drag.
6. Watch the indicator the whole drift, and set on anything unusual.
7. Adjust depth after about half a dozen drifts, using the bottom-ticking check above.

The Orvis rig lesson notes that "most people fish two nymphs at a time where it is legal to use two flies," with the second fly on about eight inches of 5X tippet. Check the stream's rules before you add a second fly; Georgia's delayed harvest rules, below, allow droppers with one single hook each.

What are the most common indicator mistakes?

Most come back to depth, size or drag:

• Setting it once and never moving it. Depth changes run to run.
• Too big an indicator. It splashes down and can spook fish on calm water.
• Not mending. A dragging indicator means a dragging fly.
• Waiting to feel the fish. By then it's often spit the fly. Set on what you see.
• Watching the wrong thing. Keep your eyes on the indicator, not the line or the bank.

Each one is a quick fix once you know to look for it. If you're not sure which is happening, change one thing at a time, depth first, and give it a few drifts before you change the next.

What do strike indicators cost?

Not much. Three examples from the sellers' own pages, checked November 4, 2026:

Orvis says the Thingamabobber "never sinks and requires no floatant." Loon calls Biostrike "reusable, biodegradable, and environmentally friendly," and adds a second use for it: a dab can go "with small dry flies to increase visibility," which helps when the fly itself is hard to see. The New Zealand kit's maker says its wool "casts like a dry fly and lands gently," and that "you can adjust the depth of your nymph. If fish start rising you can remove the indicator within a couple seconds." Orvis lists the Thingamabobber in ½-inch and ¾-inch sizes, for "looped or as a straight line connection."

When should you not use an indicator?

When the fish are on the surface. If trout are rising to insects, a dry fly fishes better than a nymph under a float.

What do Georgia's rules say about indicators?

Nothing directly. Georgia's 2026 trout regulations, as published on eRegulations, don't mention strike indicators. The rules that do apply:

• One rod: "Trout anglers are restricted to the use of one pole and line which must be handheld."
• Artificial lures only on listed streams, including "Noontootla Creek and its tributaries on Blue Ridge WMA," where "only artificial lures may be used."
• Delayed harvest streams, November 1 to May 14: anglers "use and possess only artificial lures with one single hook per lure," and "the use of additional 'dropper' lures on one line is permitted as long as each lure contains one single hook."

The state's definition of an artificial lure doesn't say whether an indicator counts as one. If you're unsure about a specific product, ask Georgia DNR. Anglers 16 and older generally need a fishing license and a trout license, per Georgia DNR's license page.

What does a guided trip provide?

If you're fishing on your own, the rig and depth steps above are the whole routine. On our trips, "your guide will provide all flies, leaders, and tippet," and on Noontootla your guide picks the flies to match what the fish are doing that day.

On the Toccoa, "all gear, flies, and instruction" are included, and "wade trips are more hands-on and great for focused instruction."

Daniel Bowman

Owner & Head Guide · Bowman Fly Fishing

Daniel has guided fly fishing trips in North Georgia for more than 10 years. He runs Bowman Fly Fishing with a team of 10 guides on the Toccoa, Soque, Etowah, Noontootla, and Tuckasegee — including private water access most anglers never get to fish.