I do a lot of them every year and use an electric fillet knife Chuck. I make a cut behind the gills and follow the backbone all the way to the tail but don't go all the way through. I flip that slab over and put my knife through the tail and cut back towards the front and press the blade down and it separates the meat from the skin. I flip the fish over and do the same on the other slab. I then use a small knife to cut out the belly bones with one small circular cut. I can do about 3 or 4 a minute like that. I do the same for crappie.