Swedish fermented fish is only one – surstromming. It is baltic heering that ferment in cans. About swedish fermented fish Bob Broke tells:
Swedes eat ripe surstromming with paper-thin hard bread and boiled potatoes, usually an almond-shaped variety that comes from the north. It has a sharp, cutting taste. Sometimes, they drink milk with it, but beer and aquavit more often accompany the dish. Some Swedes down it without a second thought to its smell; others, in order to partake of it at all, first have to rinse it in purifying soda water.