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

by | Jan 2, 2019 | 29 comments

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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Domenick Swentosky

Central Pennsylvania

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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  1. 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?


    • Hi Craig,

      Thanks for the question.

      The Mono Rig leader is essentially a French leader. But the Mono Rig system incorporates a lot more than just French nymphing.

      There are really a few different terms for the same thing. What guys call euro nymphing is often what people used to call French nymphing, combined with Czech nymphing, Polish nymphing, and Spanish nymphing. These styles were mostly distinguished by how far away you fished, direction of the cast and fly type. French nymphing was traditionally straight upstream with long casts, long leaders and small flies. These days, the guys I know don’t distinguish between the styles that much. We go out with a long leader and fish the water type in front of us at the best angle possible and with the appropriate flies for the water.

      You may see a longer taper in a French leader formula, and that’s mostly to keep thinner line out of the guides at distance. (This is one reason I prefer about 3.5-4 feet of taper before the sighter in my Mono Rig formula. But these days you’ll also find French leader formulas with thin butt sections, no transition and right to the sighter.

      Again, all of these leader formulas are really interchangeable. Remember, there are 3 things that make any Mono Rig work: use mono as a substitute for fly line, use a sighter, and fish one or limited diameters of tippet under the water.

      What I call the Mono Rig is my variation of the whole thing. And I use the Mono Rig not just for tight lining nymphs, but for indicator work, streamers and dry dropper, and I use split shot sometimes. It’s all about what YOU want to do with it.

      Make sense?

      Check out Devin Olsen’s explanation:

      Or read Nymphing the New Way by Jonathon White.

      Or look at the leader formulas in George Daniel’s book Dynamic Nymphing. Those are all essentailly French leaders.


      Email me if you like.


      • Great stuff as always.

        A slightly different perspective on the mono rig is the subject of George Daniel’s latest blog post:

        • Right on.

          I had guys asking me about some things after they watched George’s vlog lately. That is, in part, why I wrote this one.

          Lots of talk lately about going thinner with the butt sections, and I just wanted to highlight when and why we might do that or we might not.

          What I like about George is that he continues to explore new rigs and tactics on the water — he’s always looking for a new edge. Gotta love it.

      • That makes complete sense Domenick. I like the versatility that your formula provides and ability to cast given the thicker butt section, the French leaders I’ve been using are much thinner in the butt. I’ll be trying your’s out this weekend.

        • Cool.

  2. 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 you can’t have both unless you have a much shorter leader. Thanks for such a great source of information and entertainment. Tight lines.

    • For sure, Colter. We can’t have everything in one leader. That’s why I like to have a few different options in my vest. But because I don’t want to change full leaders a whole lot, I choose the butt and transition sections that I do — it’s where I choose the compromise.

      I do change out full leaders too. Which is why I use a 30-40 foot Mono Rig, rather than one that’s twice as long. I want the fly line on the spool so I can change to a regular leader and use that line sometimes.

      More on that here:

  3. 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?

    • Hi Justin,

      I think it’s great that you found the material that you like best. It’s fun to experiment with stuff and come out with a plan. I’m with you there.

      I tried fluoro butt sections, but didn’t care for them. I found them to me too stiff and hold a coil too much. They also sink a bit under the surface, which I didn’t like while fishing at distance. Remember, I do a lot of big streamer work and long distance indy work on the Mono Rig.

      The lines I tried were a #4 Sunline Tenkara line, one from P-Line and one from Seaguar. Basically the handling on all 3 was the issue. But, I didn’t try #12 like you’re using.

      I really don’t like thin lines for the Mono Rig much. .015″ is as thin as I go, basically for all the reasons I wrote about in the article above. I like the fly-line-style advantage.

      You mention density, and I know fluoro has it greater than nylon. But when I’ve put equal lengths of equal diameters on a scale, I’ve found the difference to be minimal. Have you found the same, or are you using a different line than what I’ve weighed, maybe?

      Good discussion. Cheers.


      • Your writing always throws up good discussion:-)
        I’ll try and keep this as short as possible:
        Just measured my latest batch of line. Maxima cham 12lbs 0.32mm – 0.407g for 12ft. (Interesting all other maxima I’ve measured is thicker than advertised)
        BMC sniper 8lbs 0.25mm – 0.397 for 12ft (this is my go to, pretty cheap and accurate diameter)

        I know what you mean about fluro holding coil. I wouldn’t want to have it on the reel for that reason as well as crap handling but a stretch at the beginning and it’s straight all day. I rig it so the fluro leader either attaches to 20lbs chameleon or Sunray’s micro nymph line. The Sunray rocks and actually only measures 0.45mm same as the 20lbs maxima. Pretty much the same weight too but I prefer the handling of the nymph line especially in the cold and having no memory I don’t get reel pull through.

        Out to any sensible tight-line range it’s just fluro out the tip, maxima/sunray in hand but when fishing at distance with dry, duo or streamers then it acts like a fly line and longish leader.
        I also cast more precisely with the slightly brighter BMC line as I can “spot” the line mid-flight, accuracy casting competition style.
        I’m not sure the 8lbs would work for you though with the size of fish in your rivers 😉

        • Hey Justin, thanks for weighing the materials. Looks like if you matched the diameters exactly, the BMC would weight more.

          I think where you and I diverge is that you are coming from a competition setup mindset, restricted by that leader length. Because I don’t have any such restrictions, I have the luxury of using any length leader I want, so I’m very happy to use a butt section long enough that I (almost) never have any transition in my guides. It’s all 20# Chameleon in my guides. No nail knot, needle knot, blood knots or multiple materials, just one smooth sailing line in the guides. For me, that’s my priority, especially because I shoot a lot of line while fishing streamers with the Mono Rig. It sounds like the BMC wouldn’t be a good line for handling then, especially in the slightly thicker diameter that I would choose. But I’d try it. And I might someday, so thanks for the tip, man.

          Honestly, I’m really glad that I don’t have to use a competition fly line. After trying four of them now, I find them all to be more limp than 20# Chameleon. That makes sense, because even the mono core versions are much thinner mono with a fly line coating. So, ironically, the comp line casts less like a fly line than does the mono butt section. Try explaining that one to a guy who’s never used a Mono Rig. HA!

          I like the ideas that flow from the competition scene, but at some points in rigging and fishing, the FIPS rules are a hindrance and an obstacle to me.



          • I’m not a comp Guy I just ended up with something similar but for different reasons to their 2x rod length rule for leaders. I am and have been influenced a lot by that school though.
            I do fish the same set up as you with the 20lbs chameleon straight through, I’ve fished that set up a fair bit. Enough to change the tip rings on those rods to fuji sic lined jobs. I just don’t use it for trout and grayling any more. But that’s the thing as you always say it’s about asking ourselves questions and finding our own system.

            Yeah I think casting a mono rig with a light nymph or dry is probably the most elegant of all fly fishing methods.

    • 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. I don’t like it as much as the above lines but it’s much cheaper about a 1/5 of the price of the Nissin

  4. 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.

    • Cheers.

  5. 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 plane with a thin mono rig and heavy fly.

    For a dry dropper anything below 15lb maxima chameleon makes it really challenging. I have used your slidable thingamabobber but actually prefer using a similar sized airlock strike indicator – this has slightly more mass than the thingamabobber making it easier to cast (i.e. have to rely less on the mono rig to “push” the indicator to target and can use the weight of the indicator to “pull” to target). Almost as quick to adjust / slide on the line. Slightly bigger “plop” on the surface.

    • Greg,

      I love it. We see eye to eye on most things there.

      No, I never cast in the same plane, not even with dries on a standard leader. Always some oval to it.

      I use the Belgian style with loops, arcs and ovals especially when casting heavier weight and longer distance (a lot with streamers). But even then, I tend to finish the stroke with a firm, crisp stop at the end, tucking the flies down in.

      My standard casts with average weighted nymphs on a tight line is more speedy or aggressive than what you see in Lance and Devin’s videos. It looks more like traditional fly casting. No false casting, really, just pick up with a hook set, backcast and go. I also make more of an effort to cast upstream and not across so much. Devin and Lance are clearly experts in what they do. And that’s my point, — that there are a lot of ways to accomplish the same thing. And even within an angler’s style, the river forces us to adapt and change things up by the minute.

      Regarding the TBs. I agree with all your points there too. I personally prefer the TB (slidable) because it’s a bit lighter, like you said. And I can rig it a touch faster too.

      Where do you fish, Greg?



  6. Re. mono rig: Why bother putting fly line on the reel at all? I’m looking forward to trying this rig but if the fly line doesn’t leave the reel, why bother with it?

    • Hi Ken. That’s a question that a lot of people ask. I thought the same thing, until I realized that I didn’t want to use the Mono Rig for everything. I keep a regular fly line on the spool so that I can swap out the long Mono Rig leader with a regular dry fly leader. The way I do that takes about a minute. It’s MUCH quicker than swapping out spools, and you can easily do it while standing in the water.

      It’s important to me to have that versatility.

      Here are a couple articles that explain more about why and how:


      • Dom, but then you have a loop on your regular fly line when you remove the mono rig and attach a standard tapered leader – doesn’t that suck?

          • Glad to hear, my mentors always had me cut the welded loop off and attach via a super glue splice or small barrel knot coated with UV knot sense. Welded loops were always a a big NO NO, created a hinge, splash on presentation, etc.

  7. So Dom, love your blog and advice.

    Having a hard time casting the mono rig directly upstream into the wind using a dry and trailing an emerger, any suggestions?

    • Thanks James,

      Yes, I have a lot of suggestions. But it’s hard for me to know what the trouble is without knowing your setup.

      I’ll point out, that one of the reasons I setup the Mono Rig the way I do is exactly as mentioned above — that it functions as a fly line substitute. If you start swapping out butt section materials, changing diameters, lengthening sighters, or using a bunch of 6X, for example, you will change the performance of the whole thing. There’s a reason behind every piece of the Mono Rig. And it is extremely versatile.

      So if you’ve subbed material or changed anything, then my first recommendation is to go back to the original formula.

      Second, if there is not enough weight built into your nymph to counteract the wind resistance of the dry, you can not do tight line dry dropper. The butt section can only do so much pushing. The nymph needs to do some pulling sometimes too.

      Lastly, don’t fish out too far. And build speed into the cast for distance. Do not reach to the target.



      • Am I thinking right that you can consistently accomplish the pure dry fly cast with you mono rig, ie. no weight on the end of the leader. I was managing to do using Devin’s Olson’s leader formula but only during the calm of the evening during a spinner fall but into the wind, I was struggling to straighten the leader out. I will have to review your formula but I would think you guys would be close.

  8. Hi Dom,

    You mention in this piece that “the only thing missing” from the mono rig’s capabilities as compared to traditional fly line is a standard roll cast. The article says (there is an alternative) but I’ve been unable to locate a related definition/elaboration. Could you please either point me to the article where the alternative gets addressed or comment on it here? I’m asking because I’ve fairly often encountered situations where a roll cast seemed like an entirely essential technique due to an inability to backcast and limited water selection/positioning while wading either challenging terrain and/or more crowded spots. Thank you.

    • Hi Jeff,

      Good question.

      In short, you can water haul or, if you have enough weight, use what I call a pendulum cast. The pendulum cast will be featured in the next Troutbitten video on YouTube, so keep an eye out for that.



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Domenick Swentosky

Central Pennsylvania

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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