Scientific Anglers Fly Line Breakdown - What's the right Fly Line for me?


Let’s talk trout lines! Understanding a full roster of fly lines can feel like an attempt at herding cats. With almost 70 different fly lines from S.A. to choose from, it’s no wonder that a lot of folks struggle to find the right fly line for their specific fishing scenario. For the sake of continuity, all of the fly lines that I’ll be discussing are floating-textured lines from S.A.’s Amplitude freshwater series. With this in mind, let’s enter the world of freshwater trout fly lines and see what makes sense for your specific fishing application. 


Scientific Anglers Amplitude Infinity Fly Line

The Scientific Anglers Amplitude Infinity is the jack-of-all-trades fly line. This line is a half-size heavy which makes it incredibly easy to cast on a fast action rod. Scientific Anglers dubs this line as a general-purpose taper which can target anything from trout to carp. This line also features an extended head length which makes it an absolute dream to mend. For those who like to dish out line for longer drifts while nymphing, this is a great line to look at. The Infinity taper has enough backbone to cast streamers with ease while still possessing the subtleness that dry fly anglers have come to expect with their fly lines. If you’re looking for one fly line to do it all, look no further than the Scientific Anglers Amplitude Infinity.


Scientific Anglers Amplitude MPX Fly Line

The Scientific Anglers Amplitude MPX is the quintessential floating streamer fly line. This line was designed to cast big and heavy flies through nasty wind conditions with ease. Most of the mass in the MPX is at the front of the head which makes it an incredibly easy line to cast. I’ve found that folks who are new to casting especially enjoy this line due to that earlier notion. This is also a sleeper salmonfly/big dry fly line because of its ability to cast large flies. That being said, I wouldn’t fish this line on a spring creek that requires delicate dry fly delivery and presentation. This line will cast nymph rigs without any issue, it does however struggle when it comes to mending line. 


Scientific Anglers Amplitude Trout Fly Line

The Scientific Anglers Amplitude Trout is the dry fly anglers fly line. This line was designed for casting medium-to-long length distances with dry flies or small streamers/nymphs. The Trout taper is totally capable of casting small streamers/nymphs, but the reason that most anglers gravitate towards this line is because of its wonderful dry fly presentation.  I’ve found that this rod pairs well with medium to medium-fast action rods such as the Sage Trout LL or the R.L. Winston Pure. If you’re searching for a fly line to target picky or spooky fish on the surface, the Scientific Anglers Amplitude Trout Fly Line should be under serious consideration. 


Scientific Anglers Amplitude Anadro Indicator Fly Line

The Scientific Anglers Amplitude Anadro Indicator is the ultimate nymphing line. This line is 1.5 sizes heavy to turn over the largest nymph rigs imagined. The Anadro taper was meant to be fished with stiff fast action rods on big water. The long rear taper the Anadro possesses makes this a phenomenal mending line that can still cast long distances. Alaskan anglers stand behind this line for its versatility and ability to wrangle the largest of steelhead, salmon, and trout. If you’re looking for a dedicated nymphing line, the Scientific Anglers Amplitude Anadro is the answer.


Scientific Anglers Amplitude Double Taper Fly Line

The Scientific Anglers Amplitude Double Taper is the glass and bamboo enthusiast’s perfect fly line. S.A. manufactured this fly line for the purpose of small spring creek fly fishing. The beauty of a double taper fly line is that you receive twice the fishing life out of it compared to any of the previously mentioned weight forward lines. Not only do double taper lines last longer, they excel at mending due to their elongated belly and rear taper. If your grandfather had an old glass or bamboo rod that’s now sitting in your garage, this line will help it sing!

If you still have questions regarding what fly line will suit your scenario best, please feel free to call the shop at (800) 227-7127. The Madison River Fishing Company has a dedicated group of fish heads that would love nothing more than to help answer all of your questions!

By Danny Eiden

Danny grew up fishing the Driftless region of Wisconsin focusing on warmwater species, tricking bass, northern pike and muskies with big streamers and poppers. Now a full time resident of the Madison Valley, Danny finds himself fooling Madison River trout and tying up flies while contributing to the MRFC blog.


  • Mark Grugg

    This was informative for me to consider the right fly line for my Orvis 9’5wt and Orvis 9’6wt for my Montana trip in May 2024.

  • Ricky MacDonald

    Very helpful article!

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