You just found a half open bottle of fish sauce. You bought it, used it a few times, and kept it. Now a few months have passed and you are not sure if you can continue to use it. Does the fish sauce go bad?

This situation is quite common, especially in the case of condiments such as fish sauce or oyster sauce. You buy a bottle because a recipe you wanted to try calls for it. You make the recipe once or twice, and then store the half-opened bottle, where it stays for months.

Of course, fish sauce has many uses in Southeast and East Asian cuisine, where it is a staple. But unless you’re into that cuisine, or do some research to find recipes, you probably don’t know many uses for fish sauce. No problem.

In this article, we’ll go over the storage, shelf life, and spoilage of this seasoning made from fermented fish. If you want to know more about fish sauce, keep reading.

How to preserve the fish sauce?

Storing fish sauce is much the same as storing teriyaki or soy sauce. As long as the bottle is unopened, you can store it in the pantry or kitchen, at or slightly below room temperature. Make sure it is away from sources of light and heat, as these can affect the quality of the sauce.

Once the bottle is opened, make sure that it is always tightly closed. As for where to store it once opened, Red Boat Fish Sauce recommends the fridge for the best quality.

Since this seasoning contains a large amount of salt (like soy sauce), it won’t go bad if you leave it out at room temperature for a day or a week. Or a month.

However, chilling it in the fridge will help retain its quality for longer, so it’s really up to you where you store it.

How long does fish sauce last?

Many bottles of fish sauce come with an expiration date. This date informs you of the time that the product must retain its freshness and flavor. Of course, since fish sauce does not include any perishable ingredients and is high in sodium, it will easily last for months or even years after that date. For this reason, some producers do not put any date on the label next to the bottling date.

Although fish sauce rarely goes bad in terms of food safety, its quality degrades over time. That means that after storing it for a long time, one day you may notice that the taste is softer and lacks taste.

As usual, it’s impossible to know when that will happen, especially since you’re the one who decides it’s not good enough to use it.

Let’s talk about time periods. An unopened bottle of fish sauce should easily last a year past the expiration date or 3-4 years after bottling. According to Red Boat (again), an opened bottle of refrigerated fish sauce should retain quality for at least a year. Of course, most likely, it will retain its freshness for much longer.

The above dates are estimates and only for the best quality.

How do you know if the fish sauce is bad?

As I said before, fish sauce going bad is not likely. Let’s start with a couple of situations where people might think they’re bad, but they’re not.

The first is the presence of transparent crystals at the bottom of the bottle. Those crystals are sea salt, and their formation is a natural process and does not affect the quality of the seasoning.

Second, sometimes there are some particles or clouds floating around in the sauce. They are proteins that are formed in the process of protein precipitation. It is a natural process that occurs when the fish sauce has been exposed to changes in temperature. Once again, it is harmless and does not affect the safety or quality of the product.

Now let’s move on to the signs that your fish sauce is really bad.

If there are signs of mold or yeast on the surface of the sauce or in the neck of the bottle, discard the seasoning. The same if the smell or color have changed noticeably.

If the seasoning looks and smells good, try it and decide if it’s good enough to use. As with any other food, if you’re not sure it’s safe to use, throw it away.