Opinions differ on how to actually play a fish on fly tackle. One way is to give and take line with the spare hand rather than actually use the reel. Sometimes you must play fish this way especially if a fish takes the lure at your feet when you have just completed retrieving a twenty metre cast. If the fish is large enough it will run out the coils of fly line at your feet, but if not you may have problems getting all the line back into your reel to play the fish in the normal way. Wherever possible I prefer to play the fish on the reel rather than hand play the fish with the fly line.
Lure-fishing, although widely practised on reservoirs, is far from the only way of catching reservoir trout. Plenty of trout are caught each year using imitation flies fished wet and also with floating lines and flics fished in the surface film.