Does Fish Sauce Go Bad?

So you just found a half-open bottle of fish sauce. You have bought it, used a few times, and put into storage. Now a few months have passed, and you’re not quite sure if you can still use it. Does fish sauce go bad?

Such a scenario is quite common, especially for condiments like fish sauce or oyster sauce. You buy a bottle because a recipe you wanted to try out called for it. You make the recipe once or twice, and then put the half-open bottle into storage, where it sits for months on end. Of course, there’s a number of uses for fish sauce in Southeast and East Asian cuisine, where it’s a staple. But unless you’re into that cuisine, or do some digging for recipes, you probably don’t know that many uses for fish sauce. That’s okay.

In this article, we will go through storage, shelf life, and going bad of this condiment made from fermented fish. If you would like to learn more about fish sauce, read on.

Steamed fish with vinegar sauce
Image used under Creative Commons from angelhsu

How to Store Fish Sauce?

Storing fish sauce is quite similar to storing teriyaki or soy sauce. As long as the bottle is unopened, you can keep it in the pantry or in the kitchen, at room temperature or slightly below. Make sure it’s away from sources of light and heat, as these may affect the quality of the sauce.

Once you open the bottle, make sure it’s always sealed tightly. When it comes to where to store it after opening, Red Boat Fish Sauce recommends the fridge for best quality. Since this condiment contains a copious amount of salt, it won’t go bad if you leave it at room temperature for a day or a week. Or a month for that matter. Chilling it in the fridge will help retain its quality for longer, so it’s really up to you where you store it. If you expect to store the sauce for more than 6 months, I’d recommend the fridge. The pantry should be okay for shorter periods.

Vegan Frühlingsrolle
Image used under Creative Commons from Marco Verch

How Long Does Fish Sauce Last

Many bottles of fish sauce come with a best-by date. That date informs you how long the product should retain its freshness and flavor. Of course, since fish sauce doesn’t include any perishable ingredients and is high in sodium, it will easily last for months or even years past that date. Because of that, some producers don’t put any dates on the label beside the bottling date. Of course, even though 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 might notice that the flavor is milder and the taste is lacking. As usual, it’s impossible to tell when that will happen, especially because you’re the one to decide it’s not good enough to use.

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

Fish sauce (unopened)Best by + 1 year
Fish sauce (opened)3 – 6 months12+ months

The dates above are estimates and for best quality only.

How to Tell If Fish Sauce Is Bad?

As I mentioned earlier, fish sauce going bad isn’t a likely occurrence. Let’s start with a couple of situations when people might think it’s bad, but it’s not. First is the presence of clear crystals on the bottom of the bottle. Those crystals are sea salt, and the formation of those is a natural process and doesn’t affect the quality of the condiment. Second, sometimes some particles or clouds are floating in the sauce. Those are proteins that formed in the process of protein precipitation. It’s a natural process that occurs when the fish sauce has been exposed to changes in temperature. Once again, it’s harmless and doesn’t affect the safety or quality of the product.

Now let’s proceed to the signs of fish sauce actually going bad. If there are any signs of mold or yeast on the surface of the sauce or neck of the bottle, throw the condiment out. Same thing if the smell or color changes noticeably. If it both looks and smells okay, taste it and decide if it’s good enough to use. As with any other food, if you’re not quite sure it’s safe to use, discard it.