Fish is often boned along the backbone in order to keep the stomach cavity intact for stuffing. The head and tail are left on. Use a sharp knife with a flexible blade. Here, mackerel is shown.
Slit the fish on either side of the backbone, cutting the flesh away from the bone until it is completely detached.
With scissors, snip the backbone once at the head and once at the tail.
Lift out the bone, together with the stomach contents and gills.
Fish boned through the backbone can be opened out, filled with stuffing and baked.