A trout rising at the surface is the most rewarding sight in fly fishing — and the most informative. The shape of the rise tells you what's actually being eaten and gives you the next thirty seconds of strategy.
Splashy rise. Water explodes; you see a tail or even the whole fish. Usually a chase — caddis or a stonefly skating across the surface, or terrestrials being swept by. Match with a high-floating, motion-friendly pattern: Elk Hair Caddis, a hopper, a stimulator.
Head-and-tail rise. A slow porpoising motion — head up, then a humped back, then a tail. The fish is suspended just below the film, eating emergers. Adult dry-fly patterns get refused here; tie on a CDC emerger or a trailing-shuck and fish it in the surface film.
Sip rise or dimple. A subtle swirl that barely breaks the surface, often soundless. Small adult mayfly duns or spinners. Match the size and silhouette as closely as you can — these fish are the pickiest.
Watch a rising fish for thirty seconds before casting. The cadence tells you the rhythm; the form tells you the fly. One sharp guess saves you cycling through three flies.