You filet a trout like you filet a bass, crappie or white bass. You start behind the gill plate, cut to the back bone and then follow the back bone to the tail, lay the meat over and run the knife between the skin and meat. then you cut out the rib cage. If you have a larger filet, you could slit the meat along the Y bone line just above the top edge of where the ribs were. When you bread the filet, make sure you get some in the slit to cook the small bones inside. But generally they cook in a smaller filet.