Cutting through the bullshit - The “Mono” Vs Fluoro’ debate. Monofilament vs fluorocarbon

September 24, 2014 4 min read


Monofilament vs fluorocarbon


Stroft Mono

I believe it’s Lefty that is credited with saying “There’s more bullshit in fly fishing than in a Texas cattle yard” (excuse the French)

A phrase that is no more apt than when citing the 'Fluoro vs Mono' discussion. 

What is “Mono’”

Monofilament correctly refers to a single extrusion of line regardless of the material it is constructed from- as opposed to braided or multifilament lines. Fluorocarbon as we are discussing it falls into the Mono’ group

For better or worse, Mono’ has come to describe a single extruded line made from a variety of plastics, but most commonly nylon. In truth the vast majority of leaders and tippets we use as fly anglers are in fact Monofilament by definition.

Modern lines are very different than the single extruded nylons of yesteryear, and most certainly worlds apart from the “Cat gut” my Granddad used.

Fluorocarbon aside for the moment -  Most modern mono’s are formulated from mixtures of complex thermoplastics and polymers, many are treated, annealed, coated and some even pre stretched to improve strength, abrasion resistance, UV resistance and overall performance - and, some are not.

It’s my view that a lot of what we have come to believe about the properties of Fluorocarbon is little more than “received wisdom” from the marketing department. Many of the features of fluorocarbon are often over generously promoted as benefits.   And much of it, in practical terms at least - is just plain wrong.

Here are a few of the more common misconceptions:

Fluorocarbon is not “stretchy” 

Under load Fluoro' stretches virtually the same amount as nylon based materials. However Nylon has greater elasticity - that is, it tends to recover from that stretch when load is removed. Fluoro' tends to stay elongated, and weakened as a result.

Like nylon based materials, fluorocarbon lines can stretch as little as 20% before failure or as much as 30%.

Fluorocarbon is denser than Nylon, and denser material does a better job of transmitting energy. This is perhaps why some anglers say they get a better “feel” when using Fluoro and perhaps where the "Fluoro doesn’t stretch" misnomer comes from.

Being more dense than water,  it is correct that Fluoro' essentially does not absorb water. While on paper it would seem that Fluoro' would then sink, this effect is negligible and in reality not quickly enough or with sufficient force to be of much use to fly anglers.

Cast out flat and relatively straight Fluorocarbon usually does not fully break the waters surface tension. If pulled under by the weight of a fly, it will sink - very slowly, but not to have any appreciable effect on the sink rate of the fly. A Fluoro leader does not “pull” a weighted fly down into the water column by any appreciable measure.

My observations are that both nylon and fluorocarbon leaders will sink if they break the surface tension. Both can be treated with a floatant or a sinking agent such as a fullers earth mixture to affect the desired result.

Fluorocarbon is invisible to fish.

While it is true that the refractive light index of Fluoro is closer to that of water than nylon (and hence virtually invisible to fish apparently) - this common misconception is in my opinion the single biggest load of garbage out there.

Having filmed and photographed fish, leaders and tippets for over 10 years (top side and underwater) I have never been able to see any appreciable difference between the two. 

We’ve looked at tippet material in glasses of water, controlled aquariums and in fresh and saltwater at all sorts of depths and angles - It’s easily seen.  My observations have been that both materials appear equally visible against a wide range of backgrounds. And I’m pretty certain my eyes and camera lens are not nearly as well adapted at seeing underwater as those of any fish I’ve observed. 

In short, fish can see tippet, regardless of what material it is constructed from. My arbitrary observations aside, there have been a number scientific studies done on this. One such example is Jeff Thomson “Mathematical Theory of Fishing Line Visibility"


For a given cross sectional diameter a high quality nylon material has appreciably higher break strength than Fluorocarbon. Knot strength, tensile strength, shock strength - you name it, Fluoro' consistently comes second. 
However - Do keep in mind that a cheap untreated nylon material will absorb water over time which in turn will appreciably decrease strength - by as much as 20% according to some studies. It’s also important to temper this with the fact that most top manufacturers produce coated and tempered material in order to address this characteristic and also improve UV and abrasion resistance.
Stroft Tippet and leaders - extremely strong
Stroft leader and tippet is a good example of an extremely high quality annealed and coated nylon based material. It is extremely strong and has a very low diameter.


Why “test” vs diameter matters.

The superior strength of nylon based material allows us to fish thinner tippets, and while they can still be observed, a thinner tippet will allow a fly to be behave more naturally on the water - particularly important for small dries and emergers where that elusive drag free drift is all important.

Abrasion Resistance:

Certainly a consideration when fishing the salt over Coral and rough ground, but probably of negligible benefit for most trout angers. In saying that, "hard mono” and modern annealed and coated nylon products offer abrasion resistance on par with Fluorocarbon and with the most desirable superior knot and tensile strengths -  and are a third of the cost Fluorocarbon.

My advice to most trout anglers, and particularly those starting out is to save a few bucks and go for a good quality Nylon material over fluorocarbon.

If you’re working towards “Zero defects” and doing as much as possible to help tip the odds in your favour. I’d first go for very sharp, high quality hooks, good nylon, impeccable knots and most importantly - a well practiced fly cast. 

Shop Stroft High Quality Tippet and Leader Material Here >>


6 Responses


February 08, 2018

I haven’t been a fan of fluorocarbon, not at $14 for 30 yds but have discovered a knot from the owner of of a shop here in Newport Or, doesn’t have a name but in 20 years of being challenged by guides, commercial fisherman, his knot has never lost, which means I can drop an x size or 2 and still have a strong connection, the most interesting thing with this knot is the line breaks the knot stays intact I’ve never had anther knot exhibit this trait, I also haven’t lost in about 20 challenges!!


January 16, 2018

Ur opinion about efficacy of using fluoro or mono tippet is not based on science. A human’s retina is far different from that of a trout. Trout can see infrared and humans cannot. Mono reflects infrared and fluoro does not thus making fluoro less visible to fish. The refractive index of the 2 materials has less significance. Not only do we have to think like a fish to outwit them, we have to see like a fish.

john bain
john bain

November 09, 2017

Maxima mono every time, it caught fish in the1960’s. still does it reliably now – knotted with half blood and overhand knot on the dead end – too many breaks with flouro – fishes eyesight hasn’t improved to the best of my knowledge in the interim so no need for “invisibility” !!


August 21, 2017

Nice article!
I agree with everything.
I’ll try to translate to my buddy, we were talking about it last week

M HErbert
M HErbert

August 20, 2017

So with this article why are you selling Fluorocarbon? That’s confusing.


September 30, 2014

Well said Carl! It all boils down to a good cast, a perfect presentation and the knowledge of how to fight a fish! I’ve seen too many flyfishers using the most expensive gear, but lack the ability to cast a fly and make a good knot………

Leave a comment

Comments will be approved before showing up.

Also in The Drift

Native Trout. The "Chasing Natives" Initiative and why it matters to all of us.
Native Trout. The "Chasing Natives" Initiative and why it matters to all of us.

February 19, 2019 2 min read

"Native fish are often indicator species whose health tells us much about the waters they live in. In this film we will look at the survival challenges these fish have or have had and the successes we're having in managing them, examining working solutions. Factors adversely affecting native fish around the world are often the same, such as over fishing, invasive species, habitat loss, etc"
Read More
Fly Fishing Emerger Patterns <br> - Bob Wyatt's Flies
Fly Fishing Emerger Patterns
- Bob Wyatt's Flies

February 19, 2019 3 min read

" Find a feeding fish. Our first consideration is whether the trout are feeding - if at all. If they aren’t feeding, or at least watching for food, you may as well throw stones at them. It’s easy to mistake a non-feeding trout for one that is “refusing” your offerings, when in fact its just ignoring them, or asleep. When there is little food in the water column, trout often go into a semi-dormant state. A hatch of mayflies or drift of nymphs will wake them up in short order. "
Read More
Tailing Loops and how to fix them fly casting
Tailing Loops And How To Cure Them

February 12, 2019 3 min read 7 Comments

Having seen a few tails and created more than my fair share - most entirely involuntarily - I think it best to keep things relatively simple. After-all, we're all about fly fishing rather than any in-depth analysis of casting physics.
Fly fishing and certainly fly casting is most certainly the sport of exceptions and in order to attempt to explain anything in fly casting you tend to have to generalise  -and that’s what i’m about to do.
Read More

Join Us