Bones

The main skeleton of a small or moderate-size fish, consisting of the backbone and attached rib cage, can often be separated from the meat in one piece. However, there are usually also bones projecting into the fins, and fish in the herring, salmon, and other families have small “floating” or “pin” bones unattached to the main skeleton, which help stiffen some of the connective-tissue sheets and direct the muscular forces along them. Because fish bones are smaller, lighter, and less mineralized with calcium than land-animal bones, and because their collagen is less tough, they can be softened and even dissolved by a relatively short period near the boil (hence the high calcium content of canned salmon). Fish skeletons are even eaten on their own: in Catalonia, Japan, and India they’re deep-fried until crunchy.