although there are tons of different bugs the fish can slurp as they float by (topwater and subsurface)
I have always had success using subsurface attractor patterns below i will explain why. Since the water is flowing at a fast rate a trout only has a split second to decide if it is going to bite the fly or bug that is going by them because it goes by so quickly. This is where an attractor pattern will shine. an attractor pattern may have the general profile of one bug, maybe several bugs,or doesn't look like a bug at all, but it always has buggy qualities, most attractor patterns have one of these qualities. flash: some sort of tinsel or flash to get the fishes attention. Color: a color the fish commonly see float by can be put on an attractor to con a fish into biting. and the final and most important..movement. Rubber legs, marabou, you name it. any type of material that makes a fly more lifelike is a good contribution to an attractor pattern. the combinations are endless, experiment with it.
Here are some attractor nymphs i tie for trout. (pictured below)
|Hot Wire Mega Stone|
|Nymphs i Tie for trout fishing|