Ninety percent of a river holds almost no fish. This is the single most useful thing anybody ever told me about fishing, and it took years to believe it, because a river looks broadly the same all the way along.
It is not. Fish are doing arithmetic constantly, and the sum is simple: how much food arrives here, minus how much effort it costs to stay. Almost every good lie in any water is a place where that sum comes out well.
The two questions
Stand still for a minute before you cast, and ask them in order.
Where is the food going? Current carries food along predictable lines. Wind pushes it against a bank. A feeder stream delivers it in a plume.
Where can a fish sit without working? Behind a boulder. Along the slow side of a seam. In the depression at the tail of a pool. Under a cut bank.
Where those two answers overlap, there are fish. Where only one is true, sometimes. Where neither is, you are casting to water.
Seams: the most reliable feature there is
A seam is the line where fast water runs alongside slow. You can see them: a smooth ribbon against broken water, a line of bubbles, a foam edge that holds its shape.
They matter because they solve the whole equation at once. The fast side delivers food; the slow side costs nothing to sit in. A fish parked an inch inside the slow edge eats everything the fast water brings past, for free.
Fish the seam, not the froth. Beginners cast into the fastest, most exciting-looking water; the fish are usually a foot or two to the side of it, in the quiet.
Structure is only useful with current
A sunken tree in dead water is furniture. The same tree with current running past its edge is a feeding station: the fish holds in the slack behind it and takes what the current delivers to the edge.
This is why “cast at structure” is only half an instruction. Look at what the water is doing around it. If nothing is moving past it and nothing is being delivered to it, it is probably empty.
Depth changes concentrate everything
Any place the bottom steps up or down — a drop-off, a gravel bar, the lip at the head or tail of a pool — creates a slow layer at the bottom of the step and a delivery line at the top of it.
You can read these without seeing them. Watch the surface: pace changes, subtle boils, a change from smooth to slightly rippled. Water tells you what the bottom is doing if you look at it for long enough, and ten quiet minutes of looking is worth an hour of casting.
The near bank you always walk past
Almost everyone wades in and fishes the far side, because the far side looks better. The water you just walked through was holding fish until you got there.
Fish the near margin first, from a rod length back, before you commit a boot to the water. It costs three minutes and it is the single easiest improvement most bank anglers can make.
Your silhouette on the skyline, and vibration through the bank, spook fish in shallow margins long before your fly or lure lands. Approach low, slow, and from downstream where you can.
Reading an unfamiliar water in ten minutes
- Walk a hundred metres of it before setting up, looking only at the surface.
- Mark, mentally or on paper, every seam, every pace change and every piece of structure with current on it.
- Start at the downstream end so the fish you disturb move away from the water you are about to fish.
- Fish each feature properly and move — the goal is to cover the ten percent, not to fish all of it.
- Note what the water was doing when something happened. That is the part that repeats next season.
When it does not work
Sometimes you will read a piece of water perfectly and catch nothing, because fish were not feeding, or the level had just dropped, or a cormorant worked the pool an hour before you arrived. Reading water improves your odds substantially; it does not make it fishing-shaped-vending-machine.
The thing to hold on to is that a blank day where you fished the right places is far more useful than a fish caught by accident in the wrong ones. One of those you can repeat.