There is nothing new about fishing for coarse fish with the fly I started doing it by design in the mid sixties dace and chub rudd and have gone on from there with perch roach tench and carp all on wet patterns or nymphs and buzzers. I know of one person who has caught barbel on a mayfly nymph which are a large part of there summer diet. Coarse fishing with the fly is as old as fly fishing itself.
