Monofilament fishing line, known more simply as mono, is the most popularly used fishing line on the market. It’s popularity is largely due to the fact that it is extremely cheap to produce and comes in a wide variety of diameters, tensile strengths, and colors.

What is monofilament fishing line?

Monofilament is so named because it is formed from a single piece of plastic. This is in contrast to fishing lines that use multiple pieces of material like braided lines, for example.

A large bundle of monofilament fishing line.

Manufacturers create mono by melting polymers and squeezing them through tiny holes, much like how they create pasta noodles.

Fun Fact: Dupont invented Nylon in 1938. This was the first synthetic fiber and it wasn’t long before it became widely used in textile manufacturing. A year later, they used this new invention to create and launch the first mono fishing line. When they launched it, it remained unpopular for two decades compared to braided lines due to how stiff it was.

In 1959, Dupont launched a new version called Stren. It was thinner, stronger and far more versatile. This new version, the 2nd generation, caused the line’s popularity to explode. Fishermen began to adopt the new line in droves, and other companies began to produce their own versions.

What are the pros and cons of monofilament fishing line?

Important: If you haven’t read it already, be sure to check out Fishing Line Characteristics & Why They’re So Important. This comprehensive article deep dives into all the factors that go into determining the usefulness of fishing line.

That article covers topics like tensile strength, abrasion resistance, stretch, memory, diameter, and much more. You’ll want to be familiar with these concepts and how each one affects your fishing success. In this article, we’ll be referencing those factors to describe monofilament fishing line.

As you learn about each kind of fishing line, you’ll come to realize that each has their strengths and weaknesses.

Strength & Diameter

Just about any material can be made to support any weight. However, the stronger the line gets, the thicker the line becomes. This makes it more visible to fish, creates more drag when reeling, and makes it more susceptible to wind and currents.

I like to think of these two qualities together in a strength to diameter ratio.

Mono line is generally much, much thicker per strength than other non-nylon based fishing lines. For example, KastKing makes 4 lb test monofiliament that is roughly the same diameter (0.20 mm) as the 20 lb test braided line (0.18 mm). The closest they have to 20 lb test is more than twice as thick as the braided line.


Stretch is neither a good nor a bad thing. It all depends on what you’re trying to do. Need more give and take while wearing a fish out? You’ll want line with some stretch. Want to increase your hook set rate? You’ll want line with less stretch that responds to tugging faster.

Monofilament is a very stretch material. In some cases it stretches as much as 25%. This is far, far greater than other types of line. Braided, for example, has very low, or in some cases virtually no stretch at all.

Limpness, Flexibility, and Memory

Any plastic-based fishing line with have much higher memory and much lower limpness and flexibility. If you purchase a spool of mono line and it says “Low Memory,” it is comparing it to other mono lines. It is not comparing it to other line types.

Memory and stiffness can result in it coming off of the reel in coils. This makes it snag, drag and slow down as it casts out through the rod guides. It can also results in the line popping off the reel creating birds’ nest tangles.

That said, it is much better in these regards than it was many years ago. For the first two decades after it was invented, mono line was highly ignored by consumers for these reasons. Over time, however, they are continually making improvements.

Line Color

Monofilament fishing line comes in a variety of colors all of which serve different purposes. The good thing about mono line is that most are varying degrees of transparent. In fact, most companies actually offer a “clear” version for use.

Additionally, many of the colors become more and more transparent the deeper it sets into the water. This is because it reflects light much, much differently under water than it does above.

Believe it or not, many folks swear by bright, florescent pink line because it is so easy to see for the fisherman, but so difficult to see underwater.

Conclusion & Final Thoughts

There’s a reason that monofilament fishing line is so popular. It’s incredibly cheap compared to other lines and comes in a variety of strengths, diameters, and colors. It offers excellent stretch for wearing down fish.

What kinds of fishing line do you use for fishing? Do you have different line types that you use in different situations? I would love to hear from you in the comments below.

Nicholas Cardot

Nicholas Cardot

I'm an outdoor enthusiast just taking in what this beautiful world has to offer. I hike, fish, and wander off into nature whenever I can. I also try to make it as fun for my children as possible.