My biggest trout on a flyrod. 28"Brown on a BWO dry on the Grand River in Fergus Ontario. Not a lake run fish. It was huge. I hesitate only to estimate 28" for fear of ridicule but I could hardly get my hand around his tail. The tail fin had to be 6" wide.
In PA a 23"Brown on a hopper on a wild Brook Trout Enchancement stream.
Its funny I always tell people you will catch more and bigger fish on nymphs or streamers yet my 2 biggest fish have been caught on drys. Go figure???