Dry fly fishing on small, clear-water streams can be especially productive if the angler stays as low to the ground and as far from the bank as possible, moving upstream with stealth. Trout tend to face upstream and most of their food is carried to them on the current. For this reason, the fish’s attention is normally focused into the current; most anglers move and fish “into the current”, fishing from a position downstream of the fish’s suspected lie. Trout tend to strike their food at current “edges”, where faster- and slower-moving waters mix. Obstructions to the stream flow, such as large rocks or nearby pools, provide a “low energy” environment where fish sit and wait for food without expending much energy. Casting upstream to the “edge” of the slower water, the angler can see the fly land and drift slowly back downstream.