How to Choose the Right Fly Line for Trout Fishing

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Floating weight forward fly line

Many trout anglers use a weight-forward floating fly line. It sits on the surface and allows anglers to use all types of flies. Match the weight of your fly line to your rod and reel and determine if you need a line that sits on top or sinks below the surface.

Let’s be honest: fly fishing is confusing. Not only do you have to understand the different weights of fly rods and reels, but you also need to know the different insects and habits of the fish to help you choose the proper flies. Combine those things with selecting the proper fly line, and you have a mess of information and details that are intimidating to sift through.

Fly line 

Fly line is the nylon or dacron line attached to the backing on one end and leader on the other. Usually, fly line is around 90 feet long, and its size and weight help anglers get their fly to the exact place they want. The energy stores in the fly line as you make your false casts and load up your rod to launch the fly. 

Line Weight

The first thing you need to consider is the weight of your rod and reel. If you’re using a 5-weight rod and reel, you’ll want to use a 5-weight fly line. Choosing a line that matches the size of your reel and rod is necessary to keep your setup as balanced and smooth as possible. 

Most trout anglers use rods and reels between 1 and 6-weight. They’re not huge fish and generally don’t require more than a 6-weight rod. However, certain trout are larger and weigh well over 20 pounds. If you’re targeting trout of this size, you’ll want a 7 or 8-weight rod and matching line.

Some anglers choose one size heavier to add more power when casting, but it’s not required. I like a little heavier line on my reel and rod. It helps me feel as if I have more control and power to get to the spots in the water where trout sit. 

Type of Line

Anglers have a few different types of lines to choose from for their setup. Each type of line has a specific purpose. As a diehard trout angler, I have three different types of fly line. 

Floating Line 

A floating line sits on the surface of the water. This line is perfect for rivers and streams where the water constantly flows and isn’t too deep. You can use it to throw dry flies, which will help keep them on the surface. 

It also works for nymphs and streamers. Your leader allows the nymphs and streamers to drop into the water column to find the waiting fish. Floating is ideal if you don’t want your line to dip below the surface and you want your leader and tippet to be the only things underwater. 

Sink-tip fly line
Sink-tip fly line

Sink Tip

A sink-tip line is a good choice when fishing lakes or deeper water. The front 6-10 feet of a sink-tip line drop below the surface. If you’re fishing deep pools or deep sections of lakes with nymphs and streamers, a sink-tip line gets you to the bottom faster than a floating line.

The line doesn’t sink as aggressively as a full-sink line. Plus, it’s a little easier to control. You can still make mends with the sink-tip line, and it’ll get you lower in the water where the fish sit in the middle of the day. 

Sinking Line

A sinking line gets deep fast. As soon as it hits the water, it falls below the surface. Be careful if you’re fishing rivers because it tends to get snagged. However, it’s a quality option if you’re fishing deep lakes or must get down in the water column. 

If you know the fish are feeding at the bottom, and the water is deep, a full-sink line is your best bet. 

Weight-forward floating fly line with box
Weight-forward floating fly line

Line Tapers

The final thing to consider when picking your fly line is the taper. Your fly line taper is the overall shape of the line. While many novice anglers don’t pay attention to taper, it makes a difference in how your flies perform while you’re casting and mending. 

Double Taper 

Double taper lines are old-school. Most fly lines today contain a weight-forward design, but you’ll still find double-taper fly lines for sale for specific purposes. 

Double taper fly lines have a taper that’s the same length on both ends. The main belly of the fly line is the same length and width until it reaches the tapers on either end. 

The taper ranges from one foot to six feet. If one side of the line gets worn down, you can switch the line around and have a fresher taper to work with

Most anglers who use double-tapered fly line use it for dry fly fishing in smaller waters. It helps present your flies accurately on your casts and makes the mends easier. 

The long belly of the main line makes it easy to line up your fly and make an accurate cast. Plus, a longer front taper makes it easier to lay it down gently.

A double taper fly line is not the best choice if you’re trying to cover a ton of water or fish heavy flies. You won’t be able to turn over your fly line as easily, and it doesn’t cast well into the wind. 

Weight-forward fly line on the rock.
Weight-forward fly line

Weight Forward 

Today, most anglers use a weight-forward line. Weight forward line is my personal favorite due to its versatility. Weight forward line has most of its mass towards the front of the line. The “head” (front part of the line) carries the fly and pulls the “running line” (rest of the line) with it. 

Anglers can choose different lengths of rear taper, belly, and front taper depending on the type of fishing they’re doing. Anglers can throw nymphs, streamers, and dry flies with a weight-forward line. 

Depending on the flies, you’ll have to choose different front and rear taper lengths. 

Further Understanding Taper

Once you’ve decided between weight forward and double taper line, it’s important to understand the exact taper you want. 

Front Taper

A long front taper is ideal for accurate and delicate presentations. Dry flies and small nymphs benefit from a long front taper. 

A thick and short front taper helps make casting heavy flies easier. You can turn them over and have more control over them. Streamers are easiest to throw with a short and thick front taper. 

Rear Taper

A longer rear taper means you can mend more easily and control the line while it’s on the water. More of the weight is towards the middle of the line, so you don’t have to work as hard to flip the front of it over. 

Line with longer rear taper makes throwing nymphs and dries a little easier. 


If you’re fishing rivers and streams, a weight-forward floating line will put you in a place to succeed. When you need to get deeper in the water column, start with a weight-forward sink-tip line. It’ll drop the front of your line below the surface, but not all. Finally, a weight-forward sinking line is ideal when you need to get deep and don’t have time to wait. 

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