The shelf life of canned fish is as long as 24 months, which many consumers think is because it contains preservatives. In fact, it is not. Canned food is a kind of important food processing method, which is to put raw materials in the closed container with exhaust gas and treat them with high temperature to kill various microorganisms and bacteria, destroy the activity of enzymes, prevent external pollution and oxygen from entering, so as to keep the food in a stable and edible state for a long time. Therefore, most canned fish are not added with preservatives, and consumers can eat them with confidence.