Strike Indicators – What They Are, Types, & How To Use


Article Categories: Fishing | fishing tips

One of the many ways that fly fishing is different from other types of fishing is that it can be hard to tell when you have a fish on the line. This has to do with the amount of slack that is typically in a fly fishing line. When you’re trolling, spinning, or bait fishing, your baited hook sinks and there’s not a lot of slack. To combat this, many fly fisherman use strike indicators. They operate very similarly to a bobber like you would see for spin fisherman.

The same is often not true for many fly fishing methods. In fly fishing, your fly sits on below the water surface, or just below the surface when nymphing, which makes seeing a strike difficult or impossible. Slack is often purposefully used for mending to get a natural flow, so having a strike indicator lets you know when something is tugging the end of your line below the surface. This can make the difference between reeling in your fish or losing it, so it’s important to know what strike indicators are, the types of indicators, and how to use them.

Quick Navigation:
What Is An Indicator? | When To Use | Types | Which To Use


What Is A Strike Indicator?

A strike indicator is a small float attached to a line (particularly your leader) that suspends a nymph or other fly under the water’s surface. This allows you to see when a fish has struck the fly. While it is similar to a bobber used in bait fishing (and in fact, one of the most popular strike indicators is even called the Thingamabobber), it is smaller and attaches differently to the line. Using a traditional bobber on a fly fishing line may damage your leader, spook a fish, or fall off; if you want to use a strike indicator, you should use the more technical piece of equipment designed specifically for fly fishing.

Most strike indicators attach to the leader– the piece of transparent filament that connects the flies to the weighted fly line. (If you want to know more about the difference between the different lines in a fly fishing setup, we have a guide to leader, tippet, and fly line here.) A strike indicator purpose is not only to show anglers when a fish has grabbed your fly, but also to control your fly’s depth. Many strike indicators are designed to move up and down the leader easily, so that an angler can control the distance from the float (the indicator) to the flies. This distance can help the angler control the depth of the flies in the water below. Depth control is extremely important for successful fishing.


A Dry Fly Can Be A Strike Indicator

Many situations, anglers will utilize a dry fly as a strike indicator. This can be a fantastic option as the dry fly can offer an additional opportunity to catch the fish, but also can potentially spook less fish due to the lightweight nature of some types of indicators. Strike Indicator On Fly Rod Setup

Strike Indicator On Fly Rod Setup


When Should I Use A Strike Indicator?

When nymphing areas of water in which you have to cast a distance to, anglers can’t tight line nymph, and an indicator allows the angler to get a natural drift, and control the depth of the flies even at a distance away. Therefore, nymphing with an indicator adds a ton of versatility on the water. It is an essential item for nearly all anglers.

There are lots of conditions that are improved by the use of an indicator. When you’re fishing deep water or long runs, strike indicators help keep you aware of what’s going on with your line further down or up river. Rough water conditions and muddy water can make it difficult to keep track of your fly and the end of your line, so an indicator can be really helpful here, too.

When fishing shallow and clear waters, a dry dropper rig (dry fly used as an indicator), may be a fantastic option that can offer the angler just about the best odds of catching a fish as possible.

When you’re fishing tiny dry flies, size 20 or smaller, you may need a strike indicator or a second and larger dry fly that acts like and indicator to keep track of the fly.


When Should I NOT Use A Strike Indicator?

While strike indicators are useful in many situations, not all water requires their use. When you’re fishing pocket water, you may not need a strike indicator. If you’re unfamiliar with the term, pocket water is the calm water in a stream or river that’s directly behind (“in the lee”) of an obstruction like a boulder or downed log. The normal flow of water is disrupted and the water forms a “pocket” that’s perfect for fish to feed. This water moves very slowly and is a relatively small space; a tight line nymphing method can be used.

Other types of water, like shallow riffles or water that’s shallower than three feet, also may not need strike indicators. In this water, the end of the fly line and the leader are visible– you can frequently see the trout actively taking the flies. In water like this, you often can watch takes occur without an indicator.

Truthfully, anyone can get away with a tightline nymphing setup in tons of situations. Specific tight nymphing setups allow anglers to fish at even greater distances utilizing this method effectively.

Another scenario in which you may struggle with an indicator is high wind. This is because any additional weight on the line, even something as light as a strike indicator, creates a hinge point in the line. When it’s windy, these hinge points love to get tangled up and put knots in your line. Wind in general makes fly fishing difficult, and an indicator only adds to this difficulty slightly.


Types Of Strike Indicators

There are many different types of strike indicators available to the fly fisher. From traditional cork to higher tech bubble rigs, each type of indicator has its own set of advantages and disadvantages. Strike indicators are all small and light, so if you’re not sure which one you want to use, you can always keep a couple of types in your pack and play it by ear.



New Zealand Yarn Strike IndicatorYarn is an excellent choice for a strike indicator. While it does need to be treated with a floatant, as yarn isn’t particularly buoyant on its own, the advantages of yarn outweigh this disadvantage for many anglers. Yarn indicators are highly visible and are more sensitive to the action at the end of the line than most other types of strike indicators. Because yarn is so lightweight, it lies on the water with minimal disturbance and keeps your cast nicely fluid. It also puts very little resistance on your line while you’re reeling in your catch. When your indicator gets dragged underwater by a hungry fish, it puts tension on the tippet. Too much tension can break your knots, but yarn cuts right through the water without adding much additional stress. Yarn can be cut to different sizes for different situations easily.

Our opinion is that this is the most optimal indicator for spooky fish in clear water.

Examples Of Yarn Indicators:
New Zealand Strike Indicators | Other Yarn Indicator | See On Orvis


Bubble Rig / Round Foam Ball Rig

The bubble rig is the evolution of the old DIY balloon strike indicators. The first one of these that really came into prominence was the Thingamabobber, a hollow plastic ball that’s easy to attach to the leader. Other designs followed, and injection-molded plastic bubbles are one of the industry’s most popular strike indicator options.

Air-Lock Strike Indicators

Air-Lock Strike Indicators

Bubble rigs are lightweight, easy to use, and are both durable and sensitive. They are ideal for fast, high water or water that’s rising. They come in numerous colors, including several black models that are great for spooky fish. You can also get glow-in-the-dark models for night fishing. Despite their light weight, these strike indicators tend to be some of the largest ones available and are perfect for situations where you’re in rough water or angling for larger fish. They do also have quite small options for smaller water.

The downside that some bubble rigs have is how they sit on the leader. Even the improved Thingamabobber design still tends to kink your line pretty severely, creating hinge points that easily knot up. One newer design, the Airlock Indicator, uses a small plastic screw nut over a threaded post with a slit. The slit cradles your line, and compressing the sides of it with the nut holds the line in place. This version is easier to adjust than other types of bubble rig, and most importantly, doesn’t kink your line. We highly recommend utilizing the Airlock system.

Airlock is our recommended indicator system for faster and more rough water where fish can’t be spooked easily.

Examples Of Bubble Indicators:
Air-Lock Strike Indicators | Thingamabobbers | See Thingamobber On Orvis



Foam IndicatorsClosed-cell foam indicators are a popular strike indicator type that comes in numerous designs. These range from oval-shaped stickers that you pinch around a line to larger football-shaped constructions that are held onto your leader using rubber bands. These have a range of pros and cons. Lighter, smaller stickers tend to fall off in rough water but are probably the easiest kind of strike indicator to attach. Larger “turn on strike indicators,” or TOSIs, are held on with rubber bands. They are an evolution of a much older foam design that actually used a toothpick to secure the indicator to the leader.

The TOSIs can be a little tricky to get on when your hands are cold, but they are easily adjustable and don’t hinge your line. You don’t have to tie any knots for this kind of indicator, which can be a huge advantage. The stickers don’t create a hinge point either, so if you’re planning on fishing on a windy day, foam indicators might be just what you need.

While TOSIs don’t have many downsides, there is one major caveat for sticker-style foam indicators. They do tend to fall off, and they are not biodegradable. If you’re going fishing in a low current on a calm day, you’ll probably be fine– but rougher conditions can lead to you polluting the river. That isn’t something you want to do!

Truth be told, we don’t recommend these indicators since they fall off more frequently than any other type, and we don’t like to pollute water.

Examples Of Foam Indicators:
See Foam Indicator | See On Stick On Indicators At Orvis



CorQs Strike IndicatorsStrike indicators have been around for a long time. In the US, they really became popular with the increased attention paid to nymphing starting in the 1970s, but their use predated the wave of nymphing popularity. Many of these older strike indicators were made of cork, a material that anglers today still use to help with presentation and strike indication.

Cork is heavier than the other types of indicators, which can be a nod in its favor or a disadvantage, depending on the situation. Modern cork strike indicators like CorQs, are easily spotted and stay in position on the leader without sliding around. Cork will always retain its buoyancy without needing a floatant, and the visibility you get with cork is a major reason that this tried-and-true material has its lifelong fans.

Examples Of Cork Indicators:
See CorQs | See On Orvis



Loon Outdoors Biostrike Strike IndicatorPutty strike indicators are some of the newest indicators on the market. These are perfect for the angler who wants complete control over the size and position of their strike indicator. These work by molding a little piece of floating putty into the shape you want and wrapping it around your line. The putty comes in several fluorescent colors for high visibility. It molds to the line and doesn’t spook the fish.

Putty’s biggest advantage, though, is that it doesn’t create any kind of hinge point in the line. There are no knots involved, no threading your line through something, and no potential for the line to get twisted or knotted at the attachment point. It isn’t great for long casts or really fast currents, but in most water, it will stay attached to the leader until you pull it off. Putty is more expensive than most other types of strike indicator, but you can reuse it. Putty is also available as a glow-in-the-dark product, making it perfect for night fishing. It is also biodegradable.

See Putty Indicator Examples:
Loon Outdoors Putty | See On Vail Valley Anglers


Dry Fly

Using a dry fly as a strike indicator is a very easy way to incorporate a strike indicator without having to add anything special other than an extra fly. To use this kind of strike indicator, choose a large, buoyant dry fly. Tie the dry fly as you normally would to the end of the leader, and then tie a short section of tippet material to the hook bend of the dry fly. Then, attach whatever small nymph or fly that you want to use to catch fish.

While other types of strike indicators attach in one spot and are then moved around, there’s a bit of an art to using a dry fly as a strike indicator. Your choices are limitless; you can use any size of dry fly, from a little size 18 to a big size 2, depending on what you need it to lift. The only consideration you need to make is that the indicator dry fly must be able to support the trailing nymph and not get dragged under. The larger the dry fly, the heavier the nymph it can support.

In addition to the normal advantages of the various types of strike indicators, this one comes with an extra bonus: you can fish the top of the water as well as the lower parts of the water columns. By presenting two flies (or even three), you might even be able to get a fish to hit the dry fly in the right conditions. This technique is also good for angling after spooky fish in clear water.

However, there are downsides to the “dry dropper” technique. While it’s great in shallow streams, about 5 feet deep or less, deeper water presentations don’t really work. You’ll lose this system’s visibility in deep or rough water, which decreases the utility of this type of strike indicator. Another problem with this system is the potential for tangles and knots in the leader section.  When you cast two flies in tandem, they can tangle around each other in the air or catch on to each other in the water (though most anglers will be fishing two or more flies anyways). Two hooks mean twice as many opportunities to hit a snag and get stuck, so use caution if you choose to employ this technique in a fast current or in water with lots of hazards. The biggest downside to this method is that it is harder to adjust the depth of your nymphs below as it involves cutting and tying line to do so.


Which Indicator To Use

When you’re choosing the type of strike indicator to use, it can be helpful to make your decision based on the primary variable of water condition. Remember, the strike indicator is there for you to be able to tell what’s going on at the end of the line, and to control wet fly depth. While extremely wary trout might notice and be startled by the shadow or splash of a strike indicator, most of the time it’s far enough away from the fly that your average fish won’t realize it’s there. Where the strike indicator really makes a difference is in your water conditions. We’ve put together a handy chart that can help you make your decision. Realistically, they can all be used in any situation, but the chart below indicates the better uses.

Water Speed Water Depth Water Clarity Water Flow
Cork Any Middle Depth to Deep Any (avoid ultra clear when possible) Any
Yarn Any Shallow to Middle Depth Any; best for clear water Calm to somewhat choppy.
Foam Any Middle Depth to Deep Any (avoid ultra clear when possible) Any
Bubble Rig Any Middle Depth to Deep Any (avoid ultra clear when possible) Any; best choice for rough
Putty Slow to medium Shallow to Middle Depth Any Calm
Dry Fly Any Shallow to Middle Depth Clear Calm


Ultimately, the choice of what indicator to use is up to you– if you use a strike indicator at all! But different options have different performances depending on water conditions. Keep that in mind and choosing a strike indicator will be a breeze.

Max DesMarais
Max DesMarais

Max DesMarais is the founder of Hiking & Fishing. He has a passion for the outdoors and making outdoor education and adventure more accessible. Max is a published author for various outdoor and marketing websites. He is an experienced hiker, backpacker, fly fisherman, trail runner, and spends his free time in the outdoors. These adventures allow him to test gear, learn new skills, and experience new places so that he can educate others. You can read more about him here: hikingandfishing/about