I went fly fishing for grayling on the river Wharfe recently and had a mixed bag on wet fly - grayling, small chub, and a trout. I've also had dace on flies at other. times. i've had the occasional small perch and once a roach, fishing a reservoir for trout.
There's growing interest in catching pike on flies, although it needs heavy specialised rods, lines and flies. I've never tried it, mainly because the pike fishing I do is on spate rivers with steep overgrown banks - casting a big heavy wet fly in these situations usually results in the fly getting caught up on the back cast
I think that unless you live in an area where there are rivers with fast, streamy water, probably you would be better sticking to conventional coarse fishing tackle.
