a man fly fishing while standing above a river

How to Fly Fish on a River

Photo: Stephen Matera/Tandemstock

For the best river fishing success, you need to know where to look

Learning how to “read a river”—understand what’s going on beneath its surface and where you’re likely to find fish—is one of the most important lessons in fly fishing. With fast-moving currents and complex hydraulics, river fishing can be challenging, but the rewards are great, too. There’s nothing like identifying where the river trout are and pulling one out. Here’s how. 

Get Equipped

The best rod length can vary by river, but in general you want something in between a lake rod (longer, for distant casts) and a small stream rod (shorter, for tight spaces). For average rivers, a 9-foot-6-inch, 5-weight rod will fit the bill. Match your leader to the size fly you plan on fishing, but consider going with something a little longer for potentially picky fish. Dry flies, nymphs, and streamers will all work on rivers depending on the time of year and current hatch. A dry-dropper setup where you tie a nymph to the end of your line and a dry fly slightly higher is a great technique in rivers where you’re not entirely sure what will work, and allows you to give both flies a try simultaneously. 

Also, waders are a must, especially in colder, deeper rivers. Fish habitat is not always close to the banks and you want to be able to fish for hours without risking hypothermia. 

Read the River

To read a river, you want to think like a fish. Like any animal, fish want an easy meal. A river fish doesn’t want to fight a strong current, which is hard work, but it needs the current to deliver food. 

Look for seams, where two currents meet. When faster water meets slower water, it creates a perfect lane for feeding fish. Seams cam look like a subtle line on the water’s surface, and can be created by places like the back sides of rocks or boulders, the outer bends (where current typically moves faster), vegetation or cut banks, and solid debris in the water. 

Eddies are found where fast water swirls and changes direction, creating a spot that traps insects for waiting fish. Look for bubbles on the surface. 

Riffles form in shallow spots where fast water flows over rocks. If there’s deeper water just downstream of a riffle, where the water slows and forms a pool, fish like to wait there for insects to float by. 

Tip: Consider fishing the tailwaters below dams. Dams often release the cold, oxygenated upstream water out into a tailwater, which makes an ideal trout habitat.

A man fly fishing on the South Fork of the Stillaguamish River, Central Cascades, Washington Photo: Stephen Matera /Tandemstock

Time It Right

You can pull fish out of just about any river nearly year-round, but keep in mind that, just like you, fish don’t like temperature extremes. Avoid extremely cold and hot conditions. In summer, for example, you might want to fish early or late to avoid the heat of the day.  The best strategy is to do some research on the river you’re fishing and the species of bugs it holds. Certain types of bugs hatch year-round while others have very specific timelines. Look for reports online or call a local outfitter for detailed info on a specific river.  

Practice River Fishing Techniques

Casting a line into a moving current and keeping it looking realistic, as well as functionally taught, is tricky. Get a feel for it by fishing with a three-quarter upstream cast. That involves casting from near the shore across the river at about a 45-degree upstream angle—not straight upstream and not straight across. That gives you a chance to target specific spots across the river with a good balance between getting an accurate drift and keeping the line taught, just in case you need to set the hook. 

Drift is one of the most crucial parts of tricking a fish into taking your fly and can be difficult on moving rivers. You’ll want to focus on allowing the fly to move downstream directly with the current, rather than allowing your line to pull it in any other direction. When you’re fishing the three-quarter, add an upstream flick or two if you see your line start to drift downstream of your fly. Simultaneously, pull line in to keep it taut, so that if you get a bite and need to set the hook, you’re ready. Finding the balance takes practice. 

Once you have the three-quarter cast mastered, try casting directly up or downstream: Drift will be easier to manage but you’ll need to work to keep up with the current to maintain good tension on the line. 

Another critical technique in river fishing: managing the depth of your fly when nymphing. When fish feed on nymphs (juvenile insects and other subsurface bugs), they hang out in deeper water, where the current is slower. So you want to get your nymph low, but not too low, as trout won’t generally eat anything that’s dragging along the ground (they won’t even see bugs that pass beneath them). You’ll want to put your nymph as close to their eyesight as possible. Consider adding an indicator (or easily visible dry fly buoyant enough to handle the size nymph you’re fishing) to keep your nymphs at the right depth. 

All articles are for general informational purposes.  Each individual’s needs, preferences, goals and abilities may vary.  Be sure to obtain all appropriate training, expert supervision and/or medical advice before engaging in strenuous or potentially hazardous activity.