We proceed slowly, start searching the fish with light weighted nymphs. Right under a half submerged root we spot a rise. The fish is rising with a precise rhythm, but the place is at the edge of the possible. A large half submerged dead root creates a tunnel with the bank and the rhythmic rise occurs in a surface that is a square 20 cm. right at the end of this tunnel. There is only a good cast or maybe two before the fish gets spooked. Additionally the fly has to drop into the water without alarming the fish. Such condition, with a fish that is not alarmed, makes the exactness of the imitation less absolute, here the fly just requires high-level resemblance to what the fish is taking. Precision and careful presentation are the key.