I have not connected with any grass carp yet, but, do see where the green may attract one. Tied like I presented has produced some very nice bluegill for me at one of the smaller TVA impoundment lakes here. I have so much faith in the fish catching of this pattern, that I usually start out with it no matter what species of fish I am fishing for. Like I stated above, I do use hackle in a darker shade and shorter length and for some unknown reason, and I do apologize for it, I used a longer hackle in the presentation. I try to use hackle that is about hook gape length or just a tad over.
Fly fishing and fly tying are two things that I do, and when I am doing them, they are the only 2 things I think about. They clear my mind.