Of all the intimidating aspects of fly fishing for a newbie, finding fish may be the toughest. In the fast-flowing rivers that are home to so many of the fish we target, the layman’s eye doesn’t know where to start. There’s whitewater, eddies, boils, and obstacles (or a lack thereof). How can the beginner go about simplifying all of that complexity?
The Three Pillars of a Trout Lie
If you're a fish, life is fairly simple. Take in more energy than you burn, reproduce, and don’t get eaten. Leaving spawning out of this discussion, we can boil down fish location to these key tenets.
1. Protection from Current
The first factor that plays into these survival necessities is protection from current. No fish, even those with high current tolerance, can survive by constantly fighting the current at full strength (this goes back to burning more energy than it takes in). As a result, they seek out hideaways, some very small, some very large, that protect them from current. These pockets manifest themselves in slack water behind boulders, logs jutting into the current, and the calm patches at the bases of submerged boulders. If you find places where fish are protected from current, you’ve checked one of the boxes to finding a lie.
2. Access to Food
While protection from current is important, so is access to current, or phrased differently, access to the food that is delivered by the current. This means finding slow water that is adjacent to fast water. Sure, you can find calm, relaxing water in backwaters, but these aren’t necessarily hotbeds for fish because outside of their propensity to get very warm in the summer, they are also not particularly close to the flow of food.
The "Conveyor Belt"
You can think of the current as conveyor belt, delivering food past hordes of hungry fish. The biggest fish are going to get prime position on that conveyor belt, and thus, will find the best places to rest while being as close to the flow of food as possible. If you think about it, that best enables them to take in as much food (or energy) as possible, while burning as little as they can. This metabolic relationship is absolutely essential to finding lies, and if you understand how different spots satisfy those needs (or don’t), you’ll be far better off.
3. Protection from Predators
Lastly, there’s protection from predators… aka, don’t get eaten. This is the reason you’ll find fish in deep pools when they’re not feeding - they don’t need access to the conveyor belt, and it’s a lot safer to be in the depths than it is to be fully exposed to overhead predators when feeding in a shallow riffle.
Framed this way, you can more easily explain why a fish is in any given place at any given time. When feeding, they station themselves in areas that give them protection from current and access to food. When resting, fish drop off into more protected areas, such as the tangle of wood in a logjam, beneath an undercut bank, or in the depths of a pool. This explains why you typically find actively feeding trout in riffles and runs, where current moves rapidly, and less active fish in pools. But what happens when the stars align, and all three of these core tenets are available in one spot? Enter the prime lie.
Prime Lies
Simply put, prime lies exist when a fish has protection from both current and predation, while simultaneously having access to a steady flow of food. With such an ideal set of circumstances, it’s no wonder why these areas typically hold the biggest fish in the area. They can rest, feed, and hide all in one place. Prime lies typically offer great overhead protection, shade, and other forms of cover that make it easy for the fish to retreat into a largely impenetrable hideaway.
Common examples of prime lies are downed trees in fast current, large boulders, and areas where current funnels past one distinct piece of structure. It is important to note, however, that prime lies are all relative. In rivers with cover strewn generously throughout the area, only the most protected, best-located pieces of cover will be considered “prime” (or there may be several in one area). On more barren rivers, an otherwise nondescript boulder could be the best available piece of cover.
At the end of the day, understanding fish's core needs isn't the only ingredient to becoming a consistent angler, but it goes a long way in helping you find high-percentage spots.