Yes Canned herring is fermented by pickling raw fish. Canned herring is a kind of canned fish in northern Europe. It is canned food that raw herring is canned and allowed to ferment naturally. Canned herring will produce a strong rotten smell of carrion during fermentation, which is one of the most smelly foods in the world. April-June is the herring fishing season every year, and local fishermen will catch fresh herring just caught.