Fish sauce is a condiment that is derived from fish that have been allowed to ferment. It is an essential ingredient in many curries and sauces. Fish sauce is a staple ingredient in Vietnamese, Thai, Lao, Cambodian, and Filipino cuisine and is used in other Southeast Asian countries.
In addition to being added to dishes during the cooking process, fish sauce can also be used in mixed form as a dipping condiment, and it is done in many different ways by each country mentioned for fish, shrimp, pork, and chicken. In parts of southern China, it is used as an ingredient for soups and casseroles. Some fish sauces (extracts) are made from raw fish, others from dried fish; some from only a single species, others from whatever is dredged up in the net, including some shellfish; some from whole fish, others from only the blood or viscera.
Some fish sauces contain only fish and salt, others add a variety of herbs and spices. Fish sauce that has been only briefly fermented has a pronounced fishy taste, while extended fermentation reduces this and gives the product a nuttier, cheesier flavor. Southeast Asian fish sauce is often made from anchovies, salt and water, and is often used in moderation because it is intensely flavoured.
Anchovies and salt are arranged in wooden boxes to ferment and are slowly pressed, yielding the salty, fishy liquid. The variety from Vietnam is generally called nước mắm (well known by brand names including nước mắm Phú Quốc (Phu Quoc) and nước mắm Phan Thiết (Phan Thiet)) and similar condiments from Thailand and Myanmar are called nam pla (น้ำปลา) and ngan byar yay respectively. In Lao/Isan it is called nam pa, but a chunkier, more aromatic version known as padaek is also used.
In Cambodia, it is known as teuk trei, of which there are a variety of sauces using fish sauce as a base.