Deboning a salted cod fish is slightly different than deboning a fish with a different skeletal structure. Cod fish have a long, vertical spine and a horizontal bone in the middle of the fish. To successfully remove the bones from the fish, you must cut around these main bones with a sharp knife. If the flesh resists at any time, your knife is not sharp enough. Sharpen the knife again and continue.
Place the knife along the tip of the fish's spine behind the spine. Gently separate the two halves of the fish along the spine. Cut along the same line down the length of the fish until you reach the horizontal bone near the middle of the fish.
Place the knife against the horizontal bone. Continue making the cut around the horizontal bone to avoid slicing the fillet in half. Once you reach the tail, slide the knife half way between the top and bottom of the fish, and cleanly separate the two halves along the tail line. The top half of the fish above the guts should now be in half.
Place the knife near the front of the fish on the cut line. Carefully cut down and around the fish guts and ribs with the fillet knife. Use a clean back and forth motion to separate the flesh.
Inspect the fillet for the presence of any rib or pin bones. If any remain, slide the knife behind the bones and carefully cut the bones away from the fish. You will end up with a small amount of flesh on the boned section. You can peel away the fish by hand, or discard the small piece of flesh along with the bones.
Place the fish skin side down on a cutting surface. Place the tip of the knife between the flesh and the skin and carefully cut the skin off of the fish using a back and forth sawing motion.