Fly Casting Tips/Tactics

Fly fishing the Mono Rig — Thicker leaders cast more like fly line

January 2, 2019

I love the mad scientist aesthetic of modern nymph fishing. No other form of fly fishing lends itself to so much creativity. Fact is, there are more variables in play with a nymphing rig, and there are more options for the angler to present the fly. A nymphing angler has the whole water column to use (bottom to top) while the dry fly angler has just one. The streamer angler can work the whole depth of water and can mix in a host of tactics, retrieves, lines and fly types. But let’s tell the truth — the streamer game requires a lot more cooperation from the trout. So nymphs (and wet flies to some extent) are the choice of anglers who want maximum control over the outcome — or at least for the fisherman who wants a good reason to believe his next adjustment will catch not just one trout, but a pile of them.

The best anglers explore constantly. They adapt their rigs and leaders, searching not just for the next great thing, but for the next tailored adjustment that makes their rig just a little more personal — tuned particularly for their own water and their own specific objectives.

All of this is part of the the joy in being a fly fisher. There are hundreds of ways to make things work. And because every angler brings a unique set of goals and conditions, that’s why there are so many solutions.

Knowing your own river variables and understanding your options at their baseline — that’s the key.

Photo by Austin Dando

When I give presentations on the Mono Rig, I spend more time describing why it all works than how to fish it, because I think that’s more important. If you get it — if you really understand what’s going on beyond your rod tip — you can make your own adjustments and solve your own puzzles.

Such a thorough understanding only comes from time on the water — and a lot of follow-up, thinking about fishing all day while your boots are dry.

READ: Troutbitten | Ask and Expert: For Euro Nymphing or the Mono Rig, what’s your favorite butt section material?

Thicker vs Thinner Butt Sections

The amazing thing about the Mono Rig is how much it casts like a fly line. Stand outside somewhere with casting room, and with solid casting principles you can throw 20# Maxima Chameleon with a sighter and tippet, just like a fly line. The only thing missing is a traditional roll cast (although there is a replacement).

READ: Troutbitten | Quick Tips — Put more juice in the cast

Now change out the butt section of that Mono Rig to 8# Chameleon. Again with no fly — we’re just casting the leader. Give it a try. It doesn’t work. You can no longer cast the leader like a fly line.


Because there’s not enough mass to the leader. The 20# works because it weighs enough to make a cast even by itself — to propel it out there with a rod tip. On the other hand, the 8# line falls flat. (And I don’t know any Mono Rig anglers who fish 8# butts.)

Thinner butt sections sag less. But the thinner they are, the more they lose that fly-line-style performance. As most experienced long liners will agree, that cutoff is around the diameter of 10-12# Chameleon (.010” — .013”). But line stiffness is a factor too.

Does it Matter?

Sure it does. If I’m nymphing with a tight line all day, then I may benefit from a thinner butt section that sags less. But if I add a dry fly or a Dorsey Yarn Indy as a suspender, then an extra-thin butt section presents a handicap — because I might need some power in the leader’s butt section to help push the suspender through the wind.

Likewise, if I switch to a pair of medium or large streamers on the Mono Rig, I do not want a super thin butt section. Why? Accuracy.

It’s important to recognize that I do not need the thicker butt section for pushing those streamers to the target, nor do I need it for “turnover.” (The weight of the streamers will easily carry any Mono Rig butt section to the target.) But if I’m picking up for the next cast before stripping all the way in — if I’m casting 15+ feet of line on my backcast and forward cast before shooting even more line, I lose a lot of accuracy with a thinner butt section.

Some long liners sum all this up by saying that, at a point, fishing with extra thin butt sections becomes more like lobbing than casting. And that’s a fair way to describe it. But there’s also some real finesse to a good caster who can handle an extra thin Mono Rig and a single #16 beadhead. That’s not lobbing. But when you swap out to a pair of streamers with such a thin line, then yeah, you’re back to lobbing.

Me and You

It’s really up to each angler to form his or her own objectives, to measure them against the conditions and limitations of the water ahead. Adapt, solve the puzzle and then step into the river.

Photo by Bill Dell

All of This

In the coming months (and years) I’ll dig a little deeper into more Mono Rig topics. I’d argue that everything you need to know is already contained in the other Mono Rig articles, at least in kernel form. But while many of the early Mono Rig articles on Troutbitten give a broad perspective of a full system, these coming articles will each focus on a single, key point and flush it out a bit.

Fish hard, friends.


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Enjoy the day.
Domenick Swentosky



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Craig Gravina

Hi Domenick… I’m a huge fan of troutbitten … probably the best resource for nymphing on the net!

I’m a believer in the mono rig, but have recently picked up the French leader. While I haven’t mastered it yet, it does feel like I can fish nymphs at greater distances, and works well with a suspender. I don’t think I’ve seen you write on the French leader and wonder what your thoughts are regarding this tactic. Are there situations that you’d prefer a French leader to the mono rig?


Colter Cavin

Hey Dom! Look forward to reading your articles every day and learn more in the form of seeing how others do such things. I totally agree with the thicker butt section casts way better than 8# but my leader consists of about 5 feet of 10# to roughly 13 feet of 8# and it definitely sags less than a 20# butt section as you pointed out. It works well with single and double nymph rigs and dry dropper, but it doesn’t cast a single dry very well nor the dry dropper as far as a single nymph rig. I guess… Read more »


Have your cake and eat it!
After many a year of experimenting I’ll use a fluro butt section for all my trout fishing. The greater density alows better casting for a given mass meaning you get the casting benefits of 20lbs maxima but the sag of 12lbs. I think the thinner diameter gives better control of streamers too.
Just have to rig something different in the part you handle as the fluro is too thin for that.
What do you reckon Dom?


I fish tenkara a lot and tried a lot of level lines. What brand/type fluoro are you using for this? I have found that the castability / handling of fluorocarbon can vary widely from brand to brand, even when they are claiming the same size.


Yeah they vary a lot. Often what it says on the pack is wrong too. I’ve had #2 lines measured where a #4 should be and #3.5 lines measure as #2s. I too fish Tenkara. Not so much right now but I used to fish it a lot. If I had to pick my favourite I’d say Nissin Tenkara level line in 2.5 or this sunline light pink #2 stuff I’ve got it doesn’t have much English on the pack apart from SV-I so I don’t really know what it is. Overall though I’m happy enough with the BMC shooter.… Read more »

Bob Ronnenkamp

I got to play with a challenge of fishing canal roughly 10 to 12 deep. My intention was to use 10 feet (actually 14 feet) with 11 foot switch rod. Wind over right shoulder was nightmare.
Changed location and wind direction and cast more effectively. Caught my first chunky rainbows of 2019.
Learned to fish with spinning gear, 4lb test mono and 1/32 oz jigs. Adapting this one of my flyrod styles. (Think smallmouth and walleye on Missouri river)
Love your thoughts and solutions.


How are you casting? Straight 10 and 2 in the same plane? I think you can achieve reasonable accuracy with a slight belgian cast or a loop/oval cast (as described by Devin / Lance in their videos) even with thin lines and a heavy fly (streamer even). However for this style you do need significant room behind you for your backcast/fly to rotate around in the oval and come forward over the top (this is what allows accuracy)…not always feasible in the river. Do agree that accuracy becomes terrible if the back cast & forward cast are in the same… Read more »

Domenick Swentosky

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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