8 Best Fly Fishing Knots You Should Know How to Tie

This article was originally titled "Connecting the Pieces" in Fly Fisherman's special publication Fly Fishing Made Easy.

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Tying knots is one of the foundational skills in fly fishing. As with casting, fly tying, and entomology, you can use the KISS principle (Keep it Simple, Stupid!) or you can take pride in mastering an important subdiscipline.

While tying a Bimini twist or a Duncan loop isn’t as exciting as fooling a large brown trout, it’s all part of the wonderful, complex world of fly fishing. What makes fly fishing so fascinating is the many interlocking facets, and the depths to which you can plunge into every single discipline. You don’t need specialty knots like the Albright knot or the slim beauty to get started; you can be a successful freshwater fly fisher with just the nine knots shown here.

Your backing, fly line, leader, tippet, and fly are all one continuous system, but unless you buy a preassembled package, each independent part must be connected by a knot.

The knots you use to add a tippet, or tie on a fly, you’ll have to know by rote, because you’ll do it dozens of times each day. Most other knots can be tied using a reference such as this magazine. It doesn’t make you less of a fly fisher if you need to look up a lesser-used knot like a uni knot from time to time when you get a new reel and want to add backing.

It’s also fun to try new knots. You’ll find that some knots are easier for you to tie than others, or you’ll find new methods of tying old knots. As the old adage goes, “there are many ways to skin a cat,” and there are also many ways to connect all the pieces of your fly line system—here are some trusted and time-tested methods, and the reasons behind them.

Backing 

Let’s start with your backing because if you are at home right now, starting with an empty reel, that’s the item you need to deal with first. The backing literally “backs you up” if you hook a large fish that takes out your entire fly line (about 100 feet). In trout fishing, this is a rare event, but it can happen if you are in a big, fast river, and/or you are using small flies or light tippet.

In any event, you require backing to fill up the extra space in your reel, as your reel is designed to hold a fly line plus a certain amount of backing.

Even if you don’t plan on catching anything larger than panfish, you must fill the reel arbor with the appropriate amount of backing. Otherwise your fly line will be coiled too tightly around the narrow spindle, and will be difficult to straighten and use effectively.

Some reels have a mark on the inside of the spool frame to indicate how far to fill your reel with backing. If not, fill it to about a third or half full. (Usually 100 to 150 yards of 20- or 30-pound-test Dacron for most trout reels, and more than 250 yards of backing on saltwater reels used for tarpon, billfish, or other large fish.)

It’s a good idea to buy your backing and fly line at a specialty fly shop, not only because the employees there can advise you on the best line for your local conditions, but because they have a line winder that spools line onto your reel effectively and quickly. They’ll charge you for the backing, but most don’t charge you for the service.

Winding backing onto a reel is time-consuming (150 yards at one inch per crank), and the backing must be wound tightly and evenly, back and forth across the width of the reel arbor. If you wind loose coils of backing near the base of the arbor, then wind tighter layers on top (such as when you land a large fish, or merely when you complete the job of winding the backing onto the reel) then the tight coils bury themselves under the loose coils, creating a snarl that jams your reel. Wind your backing onto the reel properly to avoid problems later.

If you can’t have a fly shop put backing on your reel, you can do it yourself but you should exercise great care in doing it right. It’s easiest to wind the backing if the reel is attached to the rod butt, so attach your empty reel to the rod in the position you intend to crank. If you cast with your right hand, you’ll probably want to crank counterclockwise with your left hand, so lock your reel onto the reel seat with the reel handle facing to the left.

Take the end of the backing from the ­product spool, thread it through the rod’s stripping guide, through the reel line guard, around the spool arbor, and back out through the line guard. This is when you use an uni knot to attach the backing directly to your spool.

To ensure that you wind the backing under tension, have someone run a pencil through the backing spool and hold the ends of the pencil so the spool turns freely. As you wind it onto the reel, the backing should pass between the pages of a phone book or under your stocking foot to create tension. I recommend running the backing through a folded towel. Then you can step on the towel to create the tension you need to wind the backing tightly.

As you crank the reel to wind the backing, move the backing back and forth across the width of the spool so it winds evenly and does not pile up on one side of the spool or the other.

Once your reel is a third or half full of backing, tie a double surgeon’s loop in the end of the Dacron backing. Make sure the loop is large enough to pass the line spool through it.

Fly Line

Most top-end fly lines today come with a welded loop at the front and back. I’ve known some old-timers who cut the loops off their lines, but this begs the question, “Why did they pay the extra money for a fly line with loops in the first place?”

You pay a premium for a line with loops, and the loops are strong enough to land any trout that swims. I’ve landed tuna and tarpon on welded loops, and have never had the front loop break on a fish.

If your fly line does not come with a rear loop, you can make a permanent whipped loop at the rear of the line that is just as strong, or stronger.

To connect the loop of backing to the loop in your fly line, pass the large backing loop through the small loop in the fly line end and then pass the whole fly line spool through the backing loop to create a loop-to-loop connection. Make sure your loop-to-loop connection is seated correctly. The loops should lock together like a reef knot (square knot); otherwise the connection is bulky and won’t easily pass through the rod guides.

You cannot use the loop-to-loop method with thin, gel-spun polyethylene backing, as under pressure it will cut through the welded loop of the fly line. If you are just getting started in fly fishing, use Dacron backing. It’s cheaper, and easier to work with.

Leader

Once your line-to-backing connection is complete, the next step is attaching the tip of your fly line to the leader—typically 7 to 12 feet of tapered monofilament, which eventually joins your tippet and fly.

As mentioned previously, most fly lines have a loop on the tip, and knotless tapered leaders also often have a loop, making it easy to connect the two. Pass the loop in the leader butt through the fly line tip loop, then pass the leader tip through the leader loop. It’s also important here to seat the loops correctly so they form a compact square knot.

If your line has no loops, there are many options to connect the leader. You can whip a loop in the line tip, or use a nail knot for a permanent streamlined connection directly to the fly line. No one uses a nail to tie a nail knot—a plastic tube like from a section of ballpoint pen works well. They are also many nail knot tools on the market to make it a little easier.

Tippet

The tippet is the final piece of monofilament between the leader and your fly. Unlike the leader, which is tapered, the tippet has a uniform diameter, and should be the same diameter or slightly thinner than the terminal end of your leader.

Monofilament means literally a “single filament,” and it can be made from nylon or fluorocarbon material.

Nylon monofilament is generally more limp than fluorocarbon, which means it is easier to seat properly, and supple materials allow your fly to move more ­freely in the water and achieve a better dead-drift.

Fluorocarbon is stiffer, and more resistant to abrasion. It is also more expensive. Its main selling point is that its light refraction index is close to that of water, which means light passes through it at much the same angle, making it less visible in the water than nylon monofilament. This “invisible line” is seen as an advantage by many anglers, especially in situations where the water is clear and the fish have sharp eyesight.

The tippet serves two purposes: Every time you change your fly, you lose a bit of monofilament. If you tie your fly directly to the leader, you will have to frequently replace it because as you switch flies, the leader becomes shorter. By attaching a 2-foot tippet section, you are constantly decreasing only the length of the addition, not the leader itself.

Also, a level-diameter tippet section—especially a fine, thin 4X, 5X, or 6X tippet—is extremely limp and doesn’t turn over and land straight like your leader. It therefore adds slack into your system, allowing you to make drag-free presentations to picky trout.

The standard knots for connecting two pieces of monofilament are the blood knot and the surgeon’s knot. There’s no need to learn both since they serve the same purpose and both are strong. Some people find the surgeon’s knot a little easier to tie. The blood knot is more streamlined and therefore less likely to pick up weeds and other debris.

Fly

Your final knot—and the most important knot in many people’s estimation because it occurs at often the weakest part of the system—is the tippet-to-fly connection. The most popular knot to attach your fly is the improved clinch knot. Although it is an easy knot to tie, and many fish have been caught with it, I won’t recommend or explain it because it’s weaker than most other knots, and you probably already know how to tie it.

One of the strongest and most dependable knots is the Pitzen knot—also know as the Eugene bend knot, 16/20 knot, or simply the fisherman’s knot.

You can find out for yourself how strong this knot is by simply tying two hooks together with a single strand of nylon monofilament. Use the Eugene bend knot on one hook, and an improved clinch knot on the other. Then, dig one hook into a board and pull the other hook with pliers. It doesn’t matter which one you pull, the improved clinch knot will break first.

Breaking strength isn’t the only consideration when you are tying a knot. If you are using 6X tippet, you want the knot to be as strong as possible because you have no margin for error, but if you are using 15-pound-test fluorocarbon, a weaker knot is still pretty strong.

Another important consideration when using heavy tippets is the way the fly moves in the water, and when you use a clinch-type knot with heavy tippet, the fly acts unnaturally stiff in the water.

The solution is the no-slip loop knot, which Lefty Kreh wrote about in Fly Fisherman 15 years ago. Soon after, permit guides were using it, then nearly all saltwater guides, and now it’s popular any time you have a heavy tippet, but you want maximum movement out of your fly.

It works because the fly isn’t rigidly connected to the tippet; it’s free to slide up and down the monofilament. Use this knot for trout streamers, for all smallmouth bass fishing, for attaching large musky flies, and for swimming steelhead flies.

The illustrations and accompanying captions in this article are from Joe Mahler’s book Essential Knots & Rigs for Trout (Headwater Books, Stackpole Books, 2010).