One thing beginning fly fishermen struggle with their first time on a trout stream is locating where fish are feeding. It's not the pattern, cast, or the retrieve that gets them in trouble, it's the presentation and figuring out how to get that fly in the strike zone. Here's a look at the four basic feeding zones on a typical trout stream and what percentage of the time you can generally find fish there. You might be surprised to find trout feed under the surface 90 percent of the time.
On the Surface
Trout rarely feed on the surface, hitting insects in the surface film no more than 10 percent of the time. It will be evident fish are feeding on the surface when you see boils at the surface, hear fish slurping bugs off the top or even jump out of the water to haul in adult aquatic insects as they emerge. This is a common sight in the evenings when mosquitoes are prevalent at the water's edge. Turn to an Elk Hair Caddis or similar dry fly when trout begin to dance on the surface.
Just Below the Surface
Same goes for the immediate subsurface bite, or the first two or three inches below the surface. Trout consume about 10 percent of their diet here as well, snacking on adult insects as they make their way to the surface. Dry flies will still work at this stage, although switching to a light nymph like a pheasant tail is probably a better idea.
Middle of the Road
While a stream's midsection might contain a majority of the water, it only holds about 5 percent of the trout's diet. Insects rarely hold in the middle layer because the currents are usually stronger here and there is also little shelter in this intermediate zone. Again, most nymphs end up here in the midsection unless they are a beadhead or fished with a small splitshot weight just before the fly.
On or Near the Bottom
Trout spend a majority of their time feeding on bottom-dwelling insects and sculpin, consuming 75 percent of their diet at or near the bottom. If you don't see fish boiling or occasionally breaking the surface, it's a good bet they're holding down below. Fishing beadheaded nymphs, heavy streamers or adding a splitshot will help get your fly down where the bottom feeders lurk.