Many places have this, either in little clay jars or thrown into barrels. Its used in cooking and as an added flavoring for food. Normally its set fish + spices (or salt) in container (barrel or ceramic jar) and let sit, take the liquid and its good to go. The fermented and spoiled remains are then either processed into another food (Romans used it as a paste to add to there food).
Basicly this could open a bunch of dishes up and give another reason for some people to spend hour on end fishing.