It is well known that many fly patterns for Carp are composed of deer hair. This material is very bouyant, due to the hollow fibres that help trap air. Also some well-known trout patterns are similarly tied with deer hair - the G&H sedge for one.
I tie a lot of deer hair carp flies that I supply to my local fishing shop. I also use the same when I go carp fly fishing.
But, I also use the pattern when trout fishing and recently, I have been doing that at my 'club' fishery in Oxfordshire. I was fishing the other evening and there was a steady ripple blowing across the lake. Some fish were moving at the edge of the ripple, presumably taking flies that were hatching in the ruffled water. I tied on a large-ish deer hair pattern and chucked it out (technical fishing term) into the ripple.
It wasn't too long before fish started to take an interest. I had a query as I retrieved the line, then another (it may have been the same fish). On another cast, I had a solid take (I felt it) but the line snapped at the fly. I was using 5X (5lb bs) nylon, which I suspect was too fine for the hook. One thing I did before using, was to clip away some of the deer hair under the shank, so that the gape was better for hooking. I have started to trim the hair under the shank for my carp flies also, as I noticed last time that a wider gape increases the hook-up rate.
I need to tie up some more deer hair patterns, both for trout and carp. With these hot sultry days, I should start my carp fishing soon. I bought the dog pellets last week from a bargain shop, so I am well set up!