Fish sauce is one of the fundamental ingredients in Thai cuisine. Like salt in western cuisines, and soy sauce for Chinese and Japanese cuisines, fish sauce is used to add a special flavor distinctive to Thai cooking. There is no Thai specialty kitchen that does not have fish sauce in the cabinet, and very few recipes that do not use it in one form or another.
Fish sauce is, in the most simple of terms, the essence of fish. Derived from the leftovers of fermented fish, it can have a rather fishy flavor or more subtle tones. The style of fish sauce is dependent on how long the fish is permitted to ferment. As a rule, the longer that it has fermented, the less it will taste like fish. High quality fish sauce has light undertones of fish as well as other flavors. Younger fish sauce will taste strongly of fish.
Fish sauce is typically thick and brown in color, a result of being fermented for nine months to a year, on average. It is either added to water or oils to make a dipping sauce, or directly added to meat and vegetables while they cook.
While it is most commonly used in Thai cuisine, it has found a place in other cuisines, such as Lao, Cambodian, Filipino and Vietnamese. It does not tend to be used in Western cuisines often, as there is less of a reliance on seafood and ensuring all catches of fish are used.
Fish sauce originally started to be used so that the small fish with little commercial value would not go to waste. As the poorer people of Thailand were also resourceful, they found that the fermentation process had the benefit of this type of sauce. As it grew in popularity, small fish were kept so that they could be used in fish sauce.
Depending on region, the ingredients of fish sauce may change. Some areas will only use one specific type of fish to make fish sauce. Others will use any fish that does not have commercial value. These variances allow for fish sauces to have different flavors and be partnered better with certain dishes. When you are selecting which fish sauce to use, you should experiment with the different types, as you can alter the final flavor just by being selective on which sauce you use.
Fish sauce can be purchased by the bottle in many stores that carry Asian goods.