If this opens a can of worms so be it, I have caught a few grass carp but never a “common” carp in my life. But, a guy on another forum said he is catching grass carp by pouring tomato juice on his Chernobyl Ant fly. It is necessary to do so or change flies after catching one because they release a flight scent that repeals future fish from that fly for a time. I know I have some V8 type juice in the frig but it already has been doctored with Tabasco and Worchestershire Sauce.