Does fish sauce go bad?

In this brief guide, we will address the question, “does fish sauce go bad” as well as other questions pertaining to the subject at hand like how much time does fish sauce take to go bad or what are some of the storage practices needed to prolong the shelf life of fish sauce.

Does fish sauce go bad?

Not quite! Fish sauce is safe to consume even after 1 year past its “best before” date. However, the taste does degrade with time. Bottled fish sauce is safe to consume within 3-4 years.

Similar to oyster sauce, fish sauce is a fermented product with a high amount of salt. According to the USDA, oyster sauce and fish sauce, when unopened, lasts about 18-24 months (2). Refrigeration ensures that commercial sauces and condiments stay fresh for a longer period of time. Shelf-stable commercial sauces 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. After opening, fish sauce or oyster sauce can be consumed within 3-6 months.

It goes bad rarely, mostly depending upon its preparation technique and storage conditions. It gradually loses its organoleptic properties such as colour, flavour and odour. 

Items like fish sauce are used in small amounts while cooking; therefore, such questions are very common, and people often wonder if it goes bad or not. Well, you have your answer now. 

As a matter of fact, fish sauce often lasts longer than its expiry date, simply because of the high sodium content. Sodium acts as a natural preservative that does not allow the growth of microorganisms. However, some bacteria, called osmophilic and halophilic microorganisms (yeasts and bacteria) can grow in food with a high amount of salt. In the case of fish sauce, which contains up to 20% by weight of salt, some moderately halophilic bacteria are involved in the spoilage. In general, the spoilage can be detected by using organoleptic tests (odor and visual evidence of spoilage such as slime or gas formation) (3).

Fish sauce will also retain its freshness and flavour after the expiry date for a good period of time before it starts to lose its efficacy and flavour. Keep in mind that it is still safe to consume. The only change you’re going to experience is a darker colour and stronger aroma due to the oxidation process.

The high consumption of fish sauce in Thailand may contribute to the high levels of people suffering from hypertension in the Country. About 25% of Thai people have hypertension. The overall hypertension prevalence amongThai adults increased from 21% in 2003 to 25% in 2014 (1).

What is the shelf life of fish sauce? 

This depends on the storage conditions and whether the package is opened or closed. An unopened fish sauce can easily last for up to 2 years at room temperature (2). Whereas, it may last even longer in the refrigerator. Keep the container properly sealed for best results.

How to tell if fish sauce is rotten or spoiled?

Being a fermented beverage, it is highly unlikely that fish sauce will spoil in a traditional sense. It can only go bad if proper hygiene and safety measures are not ensured. However, microorganisms can grow over a wide range of solute concentrations. Only a few species can grow at the high osmotic pressures characteristic of environments having either supersaturated brine and/or sugar concentrations (i.e., reduced water activity) and moderately halophilic microorganisms can grow in fish sauce (3).

The composition of fish sauce is complex and during long storage, some components can be aggregated or settled on the bottom of the container if stored for a long period, but it does not mean that your fish sauce has spoiled. 

During long storage, fish sauce, which contains fatty acids, may oxidize and produce off-odors. Oxidative rancidity generally occurs in fatty fish. Primary and secondary lipid oxidation products are the biological amino compounds, proteins, peptides, free amino acids and phospholipids; these react to produce interaction compounds and this makes the color of the product brown, causes a change in flavor and loss in aromatic nutrient elements (6).

Fish sauce is translucent liquid and does not contain any sediments when it is fresh. As time goes by, due to physicochemical changes, particles are formed and the liquid becomes cloudy due to protein and ash precipitation. Gelation and aggregation of protein molecules involves partial denaturation followed by the formation of an irreversible three-dimensional network, resulting in precipitation (4). Another possible reason for the formation of precipitation is the addition of iron fortification, when fish sauce is used as a vehicle for iron fortification programs (5).

Fish sauce has a fresh amber, reddish-brown colour which might get darker by the age. Again, it won’t be harmful for consumption until you see microbial spoilage, mold growth and experience unpleasant or foul smell. In such a case, the fish sauce should be discarded.


The shelf life of the fish sauce 

Fish sauce doesn’t last forever, its quality degrades over time. As it is one the condiments used rarely or in small quantities in food products. Moreover, only a limited number of recipes require fish sauce as an ingredient.

The shelf life of fish sauce depends upon its storage conditions. Fish sauce can last from 12 months to 24 months or even more, if stored at ideal storage conditions.

The shelf life of fish sauce can be prolonged if placed in a dark and dry area.

Packaging material or container in which it is placed also matters in prolonging the shelf life. 

Not only fish sauce, anything can go bad if not stored appropriately. Unopened fish sauce bottles can last in good quality for even about 2 years (2).

How to store the fish sauce

Fish sauce is a rich source of amino acids, minerals and vitamins. The fish sauce should be stored away from light, in a dark and dry area to avoid photolytic degradation. 

Fish sauce has low or controlled water activity which means water is very well bound to salt and other molecules, lessens the possibilities of microbial spoilage. Therefore, fish sauce can be stored at room temperature.

Why Refrigerate Fish sauce?

Like already mentioned, fish sauce contains a huge amount of sodium that naturally prevents it from going bad. However, once it is opened it is recommended to store it at refrigeration temperature after sealing it tightly. The purpose of this is to enhance its shelf life by preventing oxidative degradation of compounds (2). 

Storing it in the refrigerator is an ideal storage condition when optimal results are desired.


After all that we have discussed, it is safe to say that fish sauce can go bad. I mean, any food item will go bad if you are not storing it properly. In the case of fish sauce, the chances are highly unlikely because there is no special method involved. 


In this brief guide, we addressed the question, “does fish sauce go bad” as well as other related questions pertaining to the subject at hand like how much time does fish sauce take to go bad or what are some of the storage practices needed to prolong the shelf life of fish sauce. 


  1. Rusmevichientong, Pimbucha, et al. Dietary Salt-Related Determinants of Hypertension in Rural Northern Thailand. Int J Environ Res Public Health, 2021,18.
  2. FoodKeeper. United States Department of Agriculture. 
  3. Kim, J., Elena Enache, and Melinda Hayman. Halophilic and osmophilic microorganisms. Compendium of Methods for the Microbiological Examination of Food. 2014.  
  4. Moon, Kyung-Whan, et al. Prevention of precipitation in sand lance fish sauce by chelating agents. Food Sci Biotechnol, 2008, 17, 114-117.
  5. Chavasit, Visith, Preeyacha Nopburabutr, and Ratchanee Kongkachuichai. Combating iodine and iron deficiencies through the double fortification of fish sauce, mixed fish sauce, and salt brine. Food nutr bull, 2003, 24, 200-207.
  6. Kilinc, Berna, et al. Chemical, microbiological and sensory changes associated with fish sauce processing. Euro Food Res Technol, 2006, 222, 604-613.

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