The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
An additional piece of information. Rainbow had been recently stocked in the body of water. Could the dorsal fin erosion be from overcrowding in a fisheries farm? One problem w/ this solution is that the rainbow I caught was 13.5", isn't that much bigger than what would be the normal stocking size?