You should use some type of strike indicator if fishing a nymph or sinking midge like a zebra midge. If I am fishing for big fish in very clear water, I use a dry fly as an indicator. You should use some type of adjustable strike indicator. You want the line below the indicator to be long enough to let the fly bounce off the bottom in the beginning. If you notice the fish are feeding higher in the water column, the depth will need to be adjusted. I would fish with a size 18-20 zebra midge. They are really small, but they catch lots of fish. If the strike indicator stops or drops, lift your line to set the hook.
I don't live just to fish, but I want to fish just as long as I live.