When it comes to reading fishable water, experience is the fisherman’s most important tool. Fishermen must realize the three fundamental needs of a fish when looking at a body of water. These needs are security, low current flow and food supply. Since the fish is near the bottom of the food chain, security is its first concern. A fish must feel safe before it will attend to its other needs.


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These places are often undercut banks, drop-offs, fallen trees, rocks or bends in the river. Another vital concern for a fish is energy. A fish must find a hiding place in an area where the current is not too strong. Fighting the current all day would use up too much of the fish’s energy. The current plays another important role in the fish’s life. It brings the fish its meals.

Reading the Water for Fly Fishing
Reading the Water for Fly Fishing

The fish will watch the different types of food drift by in the current and dart out and eat what it wants. This method of feeding also helps limit the amount of energy the fish must use.

The ideal spot for a fish would be a protected area right on the edge of the current, where it can rest and feed at the same time. These ideal spots are known as holding lies. Although several fish can be found in one of these lies, the biggest fish will generally hold the best spot in the lie.

Each stream or river will be different but there are some general stream characteristics that will hold fish in almost any river. These characteristics are riffles, runs, pools and flats. These should be recognized and fished by all fishermen.

Riffles are fast, shallow and choppy parts of the stream. The faster water hitting rocks creates them. The rocks obstruct the current creating a pocket of slower water. This slower water is called “pocket water” which is ideal for holding fish.

Finding and Reading Pocket Water

Pocket water is typically formed in smaller creeks and rivers with a higher gradient.  Rocks and boulders form edges of a distinct pool.  Often the pocket will have a single exit tumbling into another pocket.

These pockets form the home for trout, with natural feeding lanes, back eddies and bubble lines.  Positioning and stealth can be the toughest part of tossing flies into a pocket.  This is intimate fishing sneaky around in the woods and brush is required.

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A Classical Run

Runs are the slower section of water that are usually below the riffles. Runs are what fisherman refers to as classic dry fly water. Runs are usually about 4 feet deep and much easier to wade then the riffles. Another important characteristic of the run is the center current.

Target structure, boulders and woody debris in a run.  Think like a fish, where can you conserve energy?  How easy can I zip out and grab a morsel of food?   

Most of the time a run will have a head and tail.  These are areas that the current have swept away the small stones leaving the biggest rocks that are to heavy for the current to move.

Fishing a run along a sweeping bank
Fishing a run along a sweeping bank

This center current will be faster and deeper than the rest of the run. The center current is referred to by the fisherman as the scum line. This can be visible to the fisherman because of the presence of bubbles and insects being carried downstream by the stronger current. Fish will often hold in the deeper water and use the center current or scum line to feed.

Deep and Dark Identifying Pools

Pools are generally easy to distinguish because they are the deepest parts of the stream. They get their name because they are often used as swimming pools. Pools are usually six feet deep or deeper and are great for fish to hold. They are usually fished with weighted nymphs and streamers in order to get the flies down to the fish. When hatches of Mayflies are thick enough the fish in these pools will come up and feed on the surface.

Identifying and Fishing a Straight Run
Identifying and Fishing a Straight Run – From my course at How 2 Fly Fish

Pools usually require a indicator nymphing setup.  The water depth is what provides security, with structure breaking the current.   Set the depth of the indicator slightly deeper than the pool.  Example: if the pool is 5 feet deep go 7 feet deep from the fly to indicator.

Another important consideration is fly weight.  I prefer to fish heavy nymphs weighted with tungsten beads and lead.  The nymph has got to get to the fish fast, so don’t be afraid of adding weight.  Your fly should touch bottom every 4 cast or so.

Fishing Flats in a River

Flats are large slow-moving sections of the stream. They are very shallow and generally the same depth from one side to the other. These areas do not hold many fish but are ideal places for fish to feed when hatches are on the water. When sufficient hatches are on the water, fish will pull out of the deeper waters onto the shallow flats. Here they can easily locate the insects and feed on them without using much energy.

However, with the shallow slower moving water, fooling these fish into taking your fly can be difficult. Careful casting and proper presentation aided with lighter leader and natural looking flies will help improve your flat fishing success.

Last Cast

All fishermen can quickly learn to recognize what should be the most productive water on a stream or river. However only fishing the river will reveal the actual best holding and feeding on the river. The knowledge of riffles, runs, pools, and flats should help get you started in learning the water you are going to fish.

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Hi David Humphries Owner of Guide Recommended. I love everything to do with fly fishing. Casting, Tying, YouTube, writing about it and even teaching. I’ve got a FREE video workshop teaching how to dry fly fish at this link How 2 Fly Fish