Mono vs. Fluorocarbon: What’s Between You and the Fish

There comes a time in every fly fisher’s life—when someone corners you in the carpark at the river, down at the pub or in fly shop and asks, 'Mono or fluoro?'

It’s not a trick question, but can feel like one.

Of course, as you probably know, it’s 'just' about what kind of material you tie between your fly line (or leader in some instances) and your fly. 

But dig a little deeper, and you find it’s also about how you fish, where you fish, and what kind of angler you are when no one’s watching.

Monofilament, or "mono" for short, has been around long enough that many of us cut our teeth on it. It's flexible, floats reasonably well, and doesn’t break the bank. It stretches just enough to forgive small mistakes, which makes it the tippet equivalent of a good fishing buddy—tolerant, dependable, and willing to let you think you’re better than you are.

The next step is Nylon copolymer – a specific kind of monofilament made from a blend of two or more nylon polymers, which are engineered for improved performance—such as increased strength, better abrasion resistance, or softer handling.

Dry fly folks like mono because of that slight buoyancy. You can grease it up and keep your fly riding high, which is the point when you’re trying to tempt a brookie sipping emergers in a lazy back eddy. Mono also has a softness to it, which means fewer snapped tippets on over-eager hooksets—a detail most of us appreciate after a long winter off the water.

The downside? Mono is easier to see underwater. Which means if you're chasing spooky trout in clear, slow-moving water, it can be like waving a red flag in front of them—albeit a very thin, very transparent one.

Then there’s fluorocarbon—the sleek, modern cousin of mono. Denser, slicker, and with a refractive index close to water itself, fluoro is the material of choice for anglers who like their flies down deep and their odds of detection low. It's also (mostly) the first choice of saltwater anglers. 

It sinks faster than mono, making it ideal for nymphing or swinging streamers. If you’re drifting a beadhead through a plunge pool or dropping a pheasant tail into a run with structure, fluoro gets you there in a hurry. It's also tough—abrasion-resistant enough to hold up against rocks, branches, and toothy fresh- and saltwater fish.

But all that tech comes at a price—literally. Fluorocarbon tends to be slightly more expensive and tying knots with it can feel like wrestling a wiry cat in a phone booth. It also doesn’t stretch much, which means when things go wrong, they tend to go wrong fast.

Here’s where it gets nuanced. You don’t have to pick a side – it's not a 'this or that' kind of situation. Use what makes sense for conditions and target species.

• Dry flies: Mono all the way. It floats, it’s supple, and it presents a fly with the kind of natural drag-free drift that trout write letters home about.
• Nymphing and subsurface: Fluoro shines here. It gets your flies down quickly and stays tough in rough water or brushy banks.
• Clear water, wary fish: Fluoro’s low visibility can make a real difference. It might be the edge you need when the fish are playing hard to get.
• On a budget: Mono still does the job, and for a lot less coin.

Some anglers get fancy and mix the two—mono leaders with fluoro tippets, or vice versa—depending on what they’re doing that day. It’s not cheating. It’s smart fishing.

It’s worth noting that neither mono nor fluoro breaks down quickly. Mono can take hundreds of years, and fluoro even longer. Which means discarded tippet isn’t just litter—it’s a legacy. Please recycle! It’s a small thing, but it’s part of the deal.

There you have the technicalities. If you want to view it from a more philosophical point of view: The choice between monofilament and fluorocarbon is a little like choosing between coffee and tea. Both will get the job done. It’s the ritual, the place, and the person holding the cup—or the rod—that matters most.

Because no matter what material you're using, there's still the cast and the presentation... And that electric moment when a fish decides you're worth its time.

And that, friends, has very little to do with polymer chemistry.