Hey don't knock it Norm, I've had some great catches of Dace using nymphs when I used to work on the Test. Apparently other species that can be caught using flies include Pike !!!
Don't know where you'd tie the trace though 
i would love to give it a go.will set myself up for fly fishing in a couple of years(course fish,that is).from what i have read,many spieces can be caught on the fly.my mates dad has started fly fishing for pike,keeps him happy inbetween salmon
trips.he does't use a trace,has a 40lb mono leeder,this is stiff enough to cast a weighty fly.i would like to see him using a wire of some kind,i don't have the knowlage to give him though
Fly fishing for Rudd off the top at the end of the day is fantastic sport.
You've seen the little devils[}]. You fire in a catapault full of maggots and draw your float into the area as usual and for the first time through the course of the day something starts to take the castors and floating maggots off the surface.
You feel the excitement rise as you tackle up a rod with bubble float and start to grease the leader. After about half an hour of the little bu***rs splashing all around bait, you go to the pub and drown your sorrows having missed every dam fish.
Not so on the fly.
If you can cast with a little finesse, you can put a floating castor right in amongst them with devistating effect....fantastic sport.
i have never fly fished in my life
but on the north level we get 4 or 5 come over from rutland water
a few times every winter just to fly fish for the pike these include the bailiffs & one of the managers.
We have a rule on our river that if your fishing for pike you must use a trace of at least 18" this never has been a problem with those. they use home made flys about 4" longand looks like there main material is mink fur.
i have known them to get up to 20+ pike to 14lb in a session between them. From what they were saying last season they go all over doing this inc ireland & have had pike to about 20lb on flys.
When I went to the CLA Game fair at Broadland there was a talk by a guy (whoes name I have forgotten who talked about Barbel on a Fly - If anyone knowes of any articles on this subject I would be very interested.
Great info, great guys, great fun, thats Maggot Drowners