Boneless

The bones in most tinned fish, sardines and mackerel especially, are soft enough after cooking to eat without noticing. Boneless tins remove them before packing, which makes the fish easier to flake into a salad, a pasta, or a sandwich, and removes the one thing that gives most people pause about whole tinned fish. It is a practical choice rather than a definitive improvement. The bones left in carry calcium and flavour; the oil keeps both regardless.