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How To Fly Fish

Is it Fly Selection?

Many (? most) fly fishers obsess over their fly selection. They carry more than a few boxes of flies at all times, and spend a good deal of the day changing flies. But I think there are four skills that have more to do with putting fish into the net than fly selection. So let’s look at each of them.

Reading the Water

Reading the water, or understanding where trout hang out, is an essential skill for fly fishers. Trout do not spread themselves evenly in a stream. In fact, it’s estimated that 70-80% of a stream holds no fish, or fish that we want to catch. So in the absence of surface-feeding fish to target, if we ply all the water with our flies, most of the time we’re fishing fish-less water.

Trout seek specific sections of a stream that offer what Louis Cahill of Gink and Gasoline refers to as the three C’s: Comfort, Cover, and Cuisine. We need to recognize and fish sections that provide the C’s.

Reading the Water, Comfort

Trout in streams live in an environment of moving water. This movement or current is both a friend and a foe. On the one hand it carries food, but on the other hand, it requires trout to expend energy to maintain their position in a stream.  If forced to continuously fight a current, trout perish in just a few days. Thus they hang out where stream structure breaks or slows the current.

In the picture below, obvious rock-structure breaks the forceful current. Trout often lie in front of such large rocks, as well as along the slow/fast seams just below them.

fly fishing the subsurface, suspension nymphing

The section of stream seen below is a trout-rich environment, with its many medium-sized rocks slowing the current. There could be a trout behind any of them.

tightline nymphing
Below, a logjam offers a break from the current as well as cover.

is it fly selection

Large bends slow the current due to friction. In addition, they usually provide deeper water and often have overhanging cover as well. In the picture below, an island provides additional structure that slows the current.

is it fly selection

In streams with a steeper gradient, falls are often followed by deep, slow glides.

fly fishing small streams

Of the three C’s, comfort is probably the most important determinant of where trout position themselves in a stream. Thus searching for and recognizing structure that slows the current is the first step in reading a stream.

Reading the Water, Cover

Cover, that is, cover from predators, is a close second to comfort as trout seek a place to hold or stay. The major predators of trout mostly come from above the water. While they include mammals, such as bears, osprey and eagles are the major threat. Thus, trout need cover from these overhead predators.

The picture below shows a common source of cover, overhanging trees and brush. This bend has likely carved out soil from under the brush, creating an undercut bank, offering further cover.

is it fly selection
Riffles, shown below, produce surface chop, offering cover. 

read trout streams

If a back eddy is present below a riffle, flotsam, a collection of bubbles/foam provides excellent cover, as seen below.

is it fly selection

As trout grow to roughly twenty inches or more, it is more difficult to find protective cover. In the absence of features shown above, deeper water, at least three feet in depth, is necessary.

A game changer is low light conditions caused by foul weather. Larger fish will leave their holds in the search for food, especially if an olive hatch occurs.

is it fly selection

The largest trout often remain hidden all day, and only venture out to feed when bright sunlight is absent. Thus dusk, or nightfall, is a great time to be on the water, especially if seeking larger fish. Caddis and some mayflies hatch at this time as well. On large western streams, a mouse pattern skittered across the surface can draw vicious strikes!

Donna on the Madison

Reading the Water, Cuisine

Food, or cuisine, is the least important of the three C’s. Trout do not need to eat every day, especially if they have been able to gorge themselves. Thus they move about in a stream, always seeking comfort and cover, and feeding only when hungry.

Aquatic insects make up the bulk of a trout’s diet, roughly 80%. When a hatch is on, it’s easy to see where the food is. But in most streams, hatches occur for only a few hours of the day. The remainder of the time, trout feed on subsurface foods, primarily nymphs. If caught in the drift,  the current carries the nymphs, just as it does bugs on the surface. Finding these focused currents is key to finding fish when a hatch isn’t present. Often, bubbles on the surface reveal the current flow, as seen in the picture below.

The best fishing is found when all three C’s are present, and we refer to such lies as “prime lies”. Fish are almost always there. When trout don’t show themselves by feeding on the surface, understanding where they hang out in a stream is paramount to a successful day on a stream. In other words, learn to put your flies where the trout lie!

Selecting a Strategy

When I pull into an access parking area, I usually see anglers rigging up. They discuss what fly to use, and often make a selection based on what “worked” last time, on this or another stream. But they have no idea what is happening on the stream at this point in time. I always walk to the water I plan to fish and take a few minutes to observe what is happening before rigging up. Is a hatch in progress? If not, I check the streamside brush with a shake to see what bugs have hatched recently. I also check a few stream-bottom rocks for nymphs, noting their size and color. Such observations help me determine HOW I will fish, not just what fly to use.

If a hatch is in progress, I don’t hesitate to fish the surface, usually with a dun/emerger tandem. The odds are in the angler’s favor when trout feed on the surface, that is, easy to see and willing fish to target. But most of the time that is not the case, and it’s time to nymph. In small to medium sized streams, I tightline with two nymphs. In larger streams, I use a dry-dropper if the water is less than three feet in depth. If deeper, I generally use a sink-tip line and fish two nymphs.

During a day of fishing, stream features, weather conditions and hatch activity change. It is important to change strategies with these changes. Many anglers trap themselves into a single strategy, and only change their flies. This limits their success.


The best of flies, presented poorly, simply do not catch fish! The aim, whether fishing the surface or subsurface, is to present the fly (flies) just as the trout see them naturally. Before making that first cast, I study the water, looking for surface-feeding fish. If I don’t see any, I look for floating debris or bubbles carried by the predominant current. This is where food is carried, and is where the trout will align themselves when looking for food.

The picture below reveals a “prime lie”, containing all three C’s. The bank slows the current and overhanging brush provides cover. An adjacent bubble-line shows where the bugs, whether nymphs, emergers, duns or spent spinners, will be present.

is it the fly

Once a target-line is identified, in this case the bubble line, I cast my flies to the line, and mend my fly line as necessary to provide the longest possible natural, drag-free drift. This is true whether fishing the surface or subsurface. If a natural drift isn’t drawing strikes, providing some action to the flies is often the key. For dry flies, adding an occasional twitch up or across stream may work. For subsurface flies, stopping the drift and allowing the flies to move upward toward the surface like an emerging nymph may work.

I think that presentation is the most difficult fly fishing skill to understand and apply. It is never mastered, only improved upon. Continuous attention to presenting the fly naturally is the key to attracting trout and drawing strikes.


Casting is a skill, not unlike a golf swing. It’s easy to cast well enough to go fishing, but it’s an entirely different story to maximize the opportunity to catch more than a few fish, especially larger fish.

It is helpful to practice casting every week, especially when just learning. Taking 15-20 minutes casting on the lawn pays tremendous dividends. I first focus on accuracy, targeting a leaf or dandelion blossom (they have to be good for something!). Next I work on increasing line-speed and hauling the line. Done for 5-10 minutes, this builds the casting muscles while learning to cast farther. Then I practice slack-line casts (Extending the Drift for Better Presentation). Good casting allows the angler to consistently place the fly on target with the first cast, even in challenging circumstances. It also reduces false casts to one most of the time, and helps extend good, drag-free drifts.

So, when the fish are not cooperating, is it the fly? Usually not; rather, it’s more likely a breakdown or lack of one of the four skills above. It takes practice and patience to develop these and consistently catch wild trout. But learning is a lot of fun!

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written by Al Simpson, February, 2023.

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