When nymph fly fishing, the angler is imitating the juvenile stage of aquatic insects. As such, all fly fishing is done underwater, not on top of it. Thus, unlike when dry fly fishing, an angler will not see a rise or the fish itself pop through the surface when gulping in a fly.

Additionally, unlike dry fly fishing, when using nymphs an angler will usually not be able to see the actual fly itself. Not being able to see the fly itself is probably what gives anglers new to fly fishing with nymphs the most problems, as it needless to say makes it more difficult to detect strikes and set the hook.

Yet another challenge of nymph fly fishing is that the nymphs are frequently floated along or just near the river bottom. As such, the nymph will constantly be bumping into underwater obstructions particularly rocks. All these little bumps cause beginner anglers to mistake these bumps for strikes (as the strike indicator will momentarily pause when the nymph hits a rock). And, of course, sooner or later, the nymph will actually hook a rock or log, leading to the fun of getting the fly unstuck from whatever it hooked.

Finally, the angler who is fly fishing with nymphs will have to use methods to get their fly down into the water. Comparatively, dry fly fishing is easy where all fishing occurs right on the surface.

Everything in dry fly fishing is two dimensional. With nymph fishing, however, the angler will need to determine how deep the trout are and then figure out how to get their fly to that depth adding a 3rd dimension to their fly fishing. To accomplish this requires being able to know how to get your nymph to the right depth, as well as making accurate casts.

To top this off, trout tend to be much more subtle when they eat nymphs. Unlike in dry fly fishing, when trout often times hit a fly really hard, trout unfortunately dont show this characteristic with nymphs. This is probably due to the fact that the bulk of a trouts diet is in the form of nymphs. Whatever the reason, though, a trout tends to slurp in nymphs gently often times just being lazy and waiting for the nymph to float right to it. Because of this, setting the hook properly (and knowing when to do it) when fly fishing with nymphs is extremely important for success.

These are the challenges of fly fishing with nymphs. And these same challenges are generally what put off many a fly fisherman from attempting nymph fishing all the more so if they just happen to be fly fishing on a river known for top-water hatches (even though the exact same river may have even better sub-surface fishing!).