What Size Leader For Saltwater Fly-fishing? Tips From A Captain

Before I became a guide, I spent a couple of years working at one of the local fly shops in Saint Augustine, FL. Having that experience afforded me the ability to understand what types of questions both the novice, as well as experienced, fisherman have. One of the most common questions I received was “What size leader should I use when saltwater fly fishing?”

The appropriate size of the leader is determined by the application in which it is being used. Considerations include the fishery, depth of water, and the species. Both the proper length and strength are dependent on these factors, so there is not a universal “best” for all situations.

Fortunately for you, I’ve spent some time putting together some helpful tips to help guide you when making your selection. I’ll go through a few alternatives that include both buying pre-made and constructing your own. For specific recommendations on my favorite pre-made leaders, head over to my Recommended Products page. There, you will find my most up to date recommendations on all things fishing.

Leader Basic Terminology

In order to understand the proper size leader for saltwater fly fishing, we first need to understand some basic terminology of the construction of a leader. A leader is a long piece of fluorocarbon or monofilament typically in the 9-12ft range that is attached to the fly-line. It is designed to serve two purposes.

  1. Keep the fish from seeing the thick, often bright, fly-line.
  2. Allow the fly at the end of the line to roll out straight.

By tapering a leader from thick to thin, it allows your casting loop to unfold straighter as the fly end will be more aerodynamic. 


Below are some definitions to leader terminology that will be used later in the article:

  • Butt-Section – The thick section of leader that is attached directly to the fly-line. This is typically between 40-60lb and is attached using a “perfection loop” knot or a “nail” knot. 
  • Class – The smallest diameter of your leader is considered your class. This will define the most common break point of your leader. Class is critically important when fishing tournaments or chasing IGFA world records. For example, a leader may taper from 60lb at the butt section all the way down to 12lb where the fly is attached. Therefore the weakest point of the leader is the 12lb section. This is the class. 
  • Bite – A section tied onto the end of the leader that the fly is attached to. The “Bite” can differ from the class and is often a thicker piece attached to the fly end when fishing for fish with abrasive mouths. For example, a typical class leader for tarpon is 20lbs. However, it is VERY unlikely to land a tarpon with a 20lb tippet as their sand paper-like mouths will wear through thin diameter leader material. To combat this, one might tie a piece of “bite” onto the end of the class leader. This will keep the breakage point at 12lb, yet provide extra strength for the piece that is around the fish’s mouth.
  • Tippet – Replacement piece tied on to the end of a leader to lengthen the leader. Leaders get shorter over time as flies are clipped off and retied, or cut due to knots from casting. Tying on a piece of tippet will allow you to replace the lost the section. Additionally, a tippet can be attached to lengthen the leader to avoid fish from seeing the fly line. 
tippet diagram
Leader/tippet diagram

Considerations Before Deciding Best Size Leader For Saltwater

There are multiple factors to consider when choosing your leader, and in particular it’s size. Personally, I would not weigh any one of them more critical than the other, so it is important to consider them all together.

The Fishery

Fishing for a living has afforded me quite a few opportunities to travel to fishing destinations. When packing my gear for a trip, I like to pre-tie my leaders. Before building the leaders, I focus on what that fishery looks like. Specifically, the clarity of the water.

Water Clarity Is Key

Knowing the water clarity of a region will instantly inform you of whether or not you can get away with a “beefier” leader or if we need to use the minimum size to avoid being seen. All fish are capable of seeing your leader, and most  gamefish have incredible sight. Whether it is a redfish in the clear waters of Destin, Florida, or a permit in Key West, a larger diameter leader is more likely to be seen. Therefore, if I’m fishing for species in the 8-20lb range in clear water, I may only use a 12lb tippet to avoid the line being seen.

water clarity
Redfish in the water when clarity is high.

On the contrary, if the water is really tannic or dirty, I can get away with a thicker leader knowing the line is less likely to be seen by the fish. 

Environmental Surroundings and Structures

Another factor to consider when examining the fishery is the environment. Places with structure such as oysters or thick grass, will require you to adjust your leader size. For these tricky environments, a thicker leader will give you more abrasion resistance and allow you to pull harder against the fish to keep them out of the structure.

This can also be said for casting under things such as mangrove trees or around pilings. If there is no structure, say on a beach with sand bottom, the leader can be reduced in diameter. Most of the fun is in the fight, so the challenge of landing fish on smaller leaders will be more enjoyable. After all, we do this because it is fun, right?

Don’t Pigeonhole Yourself

Finding a balance between the visibilities of the line versus the strength needed will require some adjustments. It is always suggested to have multiple size leaders on hand. With a loop connection built into today’s modern fly lines, changing a leader will only take a few seconds.  The question I ask myself when making a selection is, “What is the minimum size leader that I feel I could land the fish on?”

The Depth – Mono vs Fluoro

Having an idea of the depth of water the targeted fish will reside can help you determine what type of leader to use. Specifically the sink rate. Naturally, Fluorocarbon leader material will tend to sink faster and has greater abrasion resistance. If throwing flies in water depths where fish are feeding greater than 6ft under, it is advised to use a heavy fly, a sinking fly line, and a fluorocarbon leader. This will allow you to place the fly quickly into the fishes feeding zone. If fish are feeding at the surface or in shallow water that is not clear, monofilament will sink slower and provide you with extra stretch when fighting a fish. 

Fluorocarbon tends to be less visible than traditional monofilament, but is not always necessary. At the end of the day, fluorocarbon is about 3 times more expensive than monofilament. Fluorocarbon is great when casting to spooky fish in clear water, but when it isn’t, save yourself some money. You will quickly come to realize, if you haven’t already, nothing is cheap in this sport!

 Another tactic I will employ is to use a section of mono before attaching my flouro tippet. This will provide the extra stretch and keep the fly from falling as quickly, but will still allow you present the clearest option to the fish.  

Adjusting a leader on the fly.

The Species

The saying “bringing a knife to a gunfight” fits well here. If you are feeling that you are under-gunned with your leader selection, you probably are. I wouldn’t throw 10lb test leader at a 120lb tarpon unless I enjoyed losing my flies. That being said, it also isn’t really fun to throw 80lb test leaders at a 14” spotted sea trout. I like to feel nervous that the fish is equally matched as me but not that he is winning.

The advice that I would give is to match the hatch. This means I would set my leader breakage point at the amount of pressure I can put on a fish to land him. Most anglers don’t realize how difficult it is to put even 10lbs of pressure on a fish. The bend in the rod will absorb most of your pulling effort and the fish on the end of the line will only feel a fraction of the “heat” you think you are putting on the fish.


The other factors discussed previously need to be considered before making selections. However, I thought it might be helpful to provide some species-focused leader size recipes for saltwater. These are my personal recipes that I have found success with. These leaders can be purchased premade or tied in the following formulas:



As you can see, the size leader for saltwater fly fishing varies by fish. There are hundreds of saltwater species and obviously we cannot cover the formula for each one within this article. The main take away is to think about what you are targeting and the challenges you may face in their environment. For more hook-ups, it is better to use smaller. Consider the amount of pressure you will need to land a fish of its size. In addition, whether you want to make your own leaders or purchase pre-made ones from a manufacturer. For a list of my recommended leader materials be sure to visit the Recommended Products page.