What Is a Mop Fly and How to Fly Fish With It

What is a Mop Fly Feature Image

Every fly angler has a fly they consider to be a cheat code. Whenever they use it, it guarantees fish. For many, the cheat code is the mop fly. The mop fly has seen its fair share of controversy over the years, but its effectiveness is proven in many fly fishing situations.

What Is a Mop Fly, and Why Is It Controversial?

A mop fly is an insect larva and grub imitation. They’re a fairly basic pattern and usually don’t grow more than an inch or two. When tying the fly, fly tyers use old rugs, mop material, or any larvae representation.

Die-hard purist anglers have mixed feelings about the mop fly. It’s one of those patterns that seems to work regardless of where or how you’re fishing. Mop flies work as the point fly in a nymph rig and help you catch all sorts of freshwater and anadromous fish.

Its impressive effectiveness causes some anglers to refuse to use it. They see it as something that works too well and takes away some of the challenges of fly fishing. There’s nothing illegal about the mop fly, and many anglers use it.

While it’s effective, it doesn’t guarantee a fish every time. So, don’t feel you’re doing something wrong if you choose to use it. One of the main goals of fly fishing is to catch fish, and using a mop fly is a perfectly ethical way.

What Fish Species Can You Catch With a Mop Fly?

Anglers have successfully caught salmon, steelhead, trout, bass, and panfish using a mop fly. Anywhere you find nymphs or grubs, you can catch fish with them.

I always carry a few mop flies in my fly box when I fish water with various fish and conditions. I’ll carry more natural and bright colors for the more aggressive fish.

Steelhead and salmon react to bright-colored flies, so a chartreuse or pink pattern is a solid option if you need an aggressive strike.

Trout and bass respond to natural and bright patterns, so carry a few different colors when you go after fish.

When Should You Fish a Mop Fly?

There are a variety of scenarios where anglers should use mop flies. High and low water, pressured fish, and just about any other scenario you find yourself fishing.

High and Stained Water

Whether it’s runoff or a recent rain, don’t hesitate to fish mop flies. If they have a beadhead, they can get low enough in the water column to find fish and bright enough to stand out in stained water.

As they soak up water, they tend to drift slowly. So, you can dead drift them through strike zones in the high water. Don’t let the high water intimidate you. Anglers have caught fish with mops in difficult conditions forever.

Trout eat during high water, and mops help you get to where they feed. They’re versatile and help you catch trout, bass, steelhead, salmon, or panfish hanging out in high water.

A grub or nymph is exactly what fish want in stained water. It’s an easy meal they know can’t get away too easily. Let your fly drift through the fishy areas, and you’ll land fish.

Some anglers would fish streamers, fish a mop fly and see what happens.

Low Water

Fishing on a sunny day in gin-clear water doesn’t always excite fly anglers. These conditions usually mean trout are skittish and unwilling to eat anything unless it’s presented perfectly.

The mop fly can entice scared fish in low water. Drift them through pockets, near logs, and through seams. Stick with natural color and let the fly do the work.

The weight of the fly, as it gets wet, helps it drop into the water column in case the fish are sitting deep. If they’re in the middle of the water column, fish it below an indicator. Fish mops in low water. It’s an ideal search pattern that gives you an idea of what the fish want.

Pressured Fish

The mop fly stands out when you’re fishing water with pressured fish. A pressured fish eats sparingly. They know what’s at risk, but the mop fly puts them at ease for whatever reason.

Fish them through the fishy areas. Yes, your presentation has to be perfect, but the fish don’t turn ignore it like they do with other flies.

Stick with a light monofilament tippet, and don’t give up too quickly. Once you find the right color, those pressured fish won’t ignore it for long.

It’s not a guarantee, but if you’re at a loss and don’t know what else to do, try a mop fly.

How Do You Rig a Mop Fly and Fish It?

Mop flies are easy to fish. If you’re a beginner, it’s a great fly to use. They’ll provide you with some necessary confidence and allow you to figure out how fish feed and move.

They’re an inch-long nymph with a beadhead. Some anglers use them at the top of a nymph rig or below a dry dropper. Others fish it straight or below an indicator. Either one of these methods works.

Fish it like you would any other nymph. Cast it upstream of a riffle, pool, pocket, seam, cut bank, or any other fishy-looking area. As the fly drifts downstream, strip the slack from your fly line, and raise your rod tip. This allows the fly to drop into the strike zone, preventing your slack from causing an unnatural drift.

Don’t be too concerned if you’re wondering how to fish the mop fly. Follow the normal fly fishing principles, and you’ll be ready.

Fast Current Setup and Tips – Using the “Mop”

The mop fly is perfect for fast currents. The beadhead helps it get low in the water column, as does the material once wet. Depending on the depth of the water, you may need to use a sink tip line, but the weight of the fly should be enough to get it lower in the column.

If you don’t want to use a sink tip, tie on a small split shot to help increase the weight.

Once you’re fishing fast current, you’ll learn that the “strike zone” doesn’t last long. You must give your fly plenty of time to drop in the water column. Cast further upstream than you would think and be ready to mend. Any fly fisher who has spent time fishing fast current knows how many casts must be made throughout the day.

Cast upstream, get the slack stripped, and raise the rod tip. This method will present the fly most naturally. If possible, look for sections of the current where it slows. Whether it’s behind a rock, under a cut bank, or in an eddy, Fish don’t want to fight the strong current if they can help it. So, they’ll sit deep or in areas where the water isn’t moving as fast.

The Mop Fly in Slow Moving Water – Setup and Tips

You can fish the mop fly alone, in a nymph rig, below an indicator, or at the bottom of a dry dropper. Ensure you have a light enough tippet to avoid giving yourself away.

Find water with plenty of cover and structure. In slow-moving water, fish are more vulnerable. They need hiding places, so they spend time fishing near rocks, logs, or deep sections. Your fly won’t need as much time to get into the strike zone, so you don’t need to cast as far upstream to achieve a natural drift.

Let it drift past the places where fish spend time hiding. They’ll dart out from safety to get what they want.

Other Tips and Tricks for Using the Mop Fly

The mop fly is versatile. Don’t hesitate to use it in areas where you might not consider it. Odds are, it’ll surprise you with its effectiveness.

Have multiple colors of the mop fly. It’s effective, but you may not be using the proper color. Tan, black, chartreuse, pink, olive, and black are good colors.

The mop fly does not have a stealthy drift. It tumbles around in the water, and that’s okay. Let the mop fly function normally as it’s moving downstream. Don’t feel the need to overcorrect. Fish will investigate the fly.

Four Great Mop Fly Patterns

1. Traditional Mop Fly

Traditional mop flies are basic. They’re a piece of a microfiber towel, an old part of a mop, or a rug tied to a beadhead. Wrap the dubbing around the material, and you’re in business. You can fish this pattern anywhere you would like. It’ll function like a traditional nymph.

2. The Mop Dragon

The mop dragon is one of the smaller mop patterns. Anglers who fish deep water or want a more lifelike representation have success with it. Instead of a beadhead, the mop dragon has dumbbell eyes, so it gets deep fast.

3. Mottlebou Mop Fly

Mottlebou mops are tied with size 8-12 hooks. They’re obnoxious and have some dubbing near the beadhead, giving it a little more flare. Most anglers make the mottlebou their first option when fishing with mop flies. It works well as the dropper in a dry-dropper rig.

4. Shagadelic Mop Fly


If you need to fish in deep water for big fish, the shagadelic mop fly is for you. It has rubber legs, mop materials, and some dubbing that adds to its effectiveness. It gets low in the water column, and it works year-round.

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Danny Mooers is a passionate fly fishing and angling writer from Arizona. Danny loves sharing his passion for fly fishing for trout and other species through his work for Tackle Village.
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