Called nam pla in Thailand and nuoc mam in Vietnam, fish sauce is an essential seasoning ingredient in many Southeast Asian dishesFish sauce is made from salted, fermented fish. Anchovies are typical, but other kinds of seafood are sometimes used. The exact method and recipe can differ from region to region and country to country depending on what is traditional or readily available.Counter-intuitively, the longer the fish are fermented, the less fishy tasting the resulting sauce.