How to Read Your Strike Indicator

Most fly fishers use a strike indicator when fishing with nymphs. When the little plastic bubble or tuft of synthetic yarn bobs or twitches, it’s time to set the hook. A trout is taking your fly. (Or perhaps you’ve hit bottom!) It’s all about how to read your strike indicator. But your strike indicator does double duty: It indicates something else that will make or break your success on the river. It tells you whether you are deep enough.

Conventional Wisdom on How to Read Your Strike Indicator

To succeed when fishing nymphs, the trick is to get the artificial flies down to the right depth. They need to be in the trout’s window.

Conventional wisdom says that you’re not fishing deep enough if you’re not getting snagged occasionally on the river-bottom. So, when the strike indicator disappears and you’ve snagged a rock rather than hooked a fish, that signals you are at the right depth. Your nymph or nymphs are deep enough to entice the trout.

We’ve advocated for this signal in previous articles:

Nymph Fishing’s 7 Nagging Questions

Our Top Nymph and Wet Fly Patterns

The Basics of Nymph Fishing

Nymphing Re-imagined

However, there is a problem with conventional wisdom. Unless you’re fishing scud patterns, you may not need to get your nymphs to bounce along the bottom.

Yes, the fish are at the bottom of the river or stream. But they are looking up unless they are nosing around in the mud or rocks for scuds. Your nymph needs only to be deep enough to be in the river’s lower zone where the trout are feeding. But you don’t need, necessarily, to bounce your nymph off of the bottom.

A More Excellent Way to Read Your Strike Indicator

So how do you know that you’re fishing deep enough if you don’t see your strike indicator disappear occasionally because you’ve snagged the bottom?

There is another signal.

Your eyes still need to be on the strike indicator. But if the indicator is moving more slowly than is the surface current, then your nymph or nymphs are deep enough. The fact is, the current at the bottom of a river or stream moves more slowly than the current on the surface. When your nymph(s) and weight float in this slower current, they will slow down the speed of your strike indicator on the surface.

Recently, I was fishing for “runners” on the Madison River just outside West Yellowstone, Montana. On a particular run, my two-nymph combination never once caught on the bottom. Yet I knew I was deep enough because my strike indicator was moving along more slowly than the surface current. After a few casts, my indicator disappeared, and I had the joy of fighting and landing a heavy brown trout.

Watch the Bubbles to Read Your Strike Indicator

This raises another question, though.

How in the world can you tell if your strike indicator is moving more slowly than the surface current?

Watch the bubbles on the surface of the water. That’s right. The bubbles tell the tale. It’s like watching a NASCAR race and seeing cars getting passed or lapped. If the bubbles on the river’s surface start passing your indicator, then you have reached the right depth. If the bubbles never pass your strike indicator, then you need to add more weight. Your nymph has not reached the slower current in the bottom zone.

Watching for the bubbles to start passing your strike indicator will also reveal how long it takes for your nymphs to reach the proper depth in the particular run you are fishing. It may take two feet or fifteen feet depending on the speed of the current and the depth of the run. This is important because it might reveal that your nymphs are getting deep enough after they drift through the spot where you suspect the fish are feeding. Armed with this insight, you can cast farther upstream so that your offering reaches its depth right before it enters the hot zone.

As always, keep your eye on the strike indicator. It gives the signal when you have a strike. But it will also tell you if you’re going to have a chance at a strike because your nymph rig has reached its proper depth.