Can you leave out fish sauce?

In this article, we will answer the following question: Can you leave out fish sauce? We explain how fish sauce is made so that you understand better why it has such a long shelf life. 

Can you leave out fish sauce?

There are more than 2,800 fish sauce production facilities in Vietnam, which has been producing more than 200 million liters per year, worth over VND 4,800 billion. However, Vietnam’s fish sauce exports account for only about 3–5% of the production. The leading cause of the current low export volume is that there are no well-established brands of Vietnamese fish sauce overseas (1).

You can leave out fish sauce up to a few years, it is not mandatory to refrigerate it once opened. Unlike ketchup or mustard, fish sauce or soy sauce has a much longer shelf life. Fish sauce can last up to 2/3 years

The soy sauce, when unopened, lasts about 3 years, according to the USDA (2). Refrigeration ensures that commercial sauces and condiments stay fresh for a longer period of time. Shelf-stable commercial soy sauce and teriyaki sauce are safe when stored at room temperature after opening. Quality, not safety, is the reason the labels on these products suggest that they be refrigerated after opening.  The soy sauce is already fermented and for this reason, does not require refrigeration. Fermented foods last much longer and are less likely to spoil over time. However, if you plan to keep it for longer than a year, refrigerating may be your best option. While fish sauce is not completely fermented, it has a long shelf life.

Among the sauces that you must refrigerate after opening are (2):

  • Black bean sauce
  • Hoisin sauce
  • Oyster sauce
  • Plum sauce
  • Sweet and sour sauce.

How is fish sauce made?

The fish sauce is an aromatic liquid, with a salty, reddish-brown taste. It is one of the basic ingredients of Thai cuisine (it is also widely used in Laos, Cambodia, Vietnam). Playing the role of salt in Western cuisine, or soy sauce in Chinese cuisine, the good quality fish sauce adds a special flavor. Basically, without fish sauce, Thai cuisine would not be the same.

Called “Nam plah”, or “nam pla”, in Thai (literally means “fish water”), fish sauce is actually the juice extracted from fish meat, through a long process of salting and fermentation. Small fish are generally used, which do not have a special commercial value. For the sauce to have a special aroma and taste, the fish must be very fresh. 

As soon as the fishing boats return with their catches, the fish is cleaned and drained, then mixed with sea salt. It is transferred to large earthen vessels, the bottom of which is covered with a layer of salt; a layer of salt is also placed on top of the fish. 

The heavy, wooden lid that covers the barrel is additionally heavy with stones, or weights, to prevent the fish from floating above the liquid that forms during fermentation. While the salting process is going on, the hydrolysis of fish tissues by fish gut enzymes provides the necessary nutrients for bacterial fermentation to begin. The length of time that is needed for the full flavor of fish sauce to develop varies from 8 to 18 months (3).

After the fermentation process, the liquid is removed from the vessels, preferably through a mouth at the base of the vessel, thus being forced to pass through the remaining layers of fish. The juice is strained, and the sediments are removed. 

The finished product is 100% fish sauce of the best quality, first hand. The intermediate qualities, the second and third hand, are obtained by adding brine  that covers the fish left in the dishes; leave to stand for 2-3 months each time, then filter before bottling. 

Finally, the remaining fish is boiled with salt water, then strained, producing the poorest quality of the fish sauce. The aroma and taste are getting weaker and weaker as the quality of the sauce decreases. Therefore, some top-quality quantities are added in the lower grades to improve them.

Salting techniques have been improved from the traditional methods. Salting by hand is being replaced by the machines. The types of machines often used in fish sauce factories are either cascade type or drum mixer type. Salting by hand can be very slow due to the small amount of fish that can be salted at any given time in order to make sure that all fish is salted uniformly. Fish may be spoiled before salting is complete. Salting and mixing machines can speed up the process. New fermentation tanks equipped with a recycling system are now under testing at commercial scales. It is claimed that this new technique will cut the production time by more than half and that fish sauce can be produced under full hygienic control (3).

Fish sauce not only works wonders in Southeast Asian dishes but is also very healthy. It contains many proteins (about 10%) and the full range of amino acids needed by the body for growth and regeneration; it also has a rich content of vitamins, especially B12, and other natural nutrients (calcium, phosphorus and iron) (3). It is much healthier to use fish sauce instead of salt, or fish sauce mixed with hot peppers instead of salt and pepper.

Few know that fish sauce, in fact, has Mediterranean origins. The Romans especially appreciated this salted fish extract, probably varieties such as anchovies, which they called “garum”, or “liquamen”; many gave this liquid magical powers!

Although they forgot it in time, the Romans were right: the fish sauce is really magical. Somewhat unappetizing in flavour, when added to food it radically transforms them. I have never eaten anything tastier, lighter and more flavorful than Southeast Asian food! 

Fortunately, it is found on the market, in almost all supermarkets and is not expensive. Overcome prejudices and use it: it will give you magical powers in the kitchen!

Other FAQs about Sauces which you may be interested in.

Does Worcestershire sauce have to be refrigerated after opening?

Does Thai fish sauce taste fishy?

Final thoughts

In this article, we answered the following question: Can you leave out fish sauce? We explained how fish sauce is made and why it has such a long shelf life.

The bottom line is that fermented foods last much longer and are less likely to spoil over time. However, if you plan to keep it for longer than a year, refrigerating may be your best option. While fish sauce is not completely fermented, it has a long shelf life.

If you have any questions or comments on the content, please let us know.


  1. Tran, Quang Hieu, Thanh Tan Nguyen, and Kim Phuong Pham. Development of the high sensitivity and selectivity method for the determination of histamine in fish and fish sauce from vietnam by UPLC-MS/MS. Int j analyt chem, 2020.
  2. FoodKeeper. United States Department of Agriculture.
  3. Saisithi, P. Traditional fermented fish: fish sauce production. Fisheries processing. Springer, Boston, MA, 1994. 111-131.