People who are new to fish sauce tend to have these question: How long does a bottle last? How to store fish sauce? The answer isn’t set because it depends on what kind of fish sauce you have and how often you use it. Once opened, a bottle of fish sauce can last a long time -- 2 to 3 years (maybe even longer). Hopefully you’ll go through a bottle of nuoc mam faster than those estimates.
Keeping things real here, my kitchen isn’t tidy, but I’m going to let you peek inside my fridge, condiment cabinet and pantry (a dark hall closet). I spread my fish sauce stash in all three of those spots. The explanation below will hopefully explain my strategies.
Fish Sauce Storage Basic Know-How
Let’s get this over with. You do not have to refrigerate fish sauce. In an article published at The Takeout, Cynthia James at Cornell University’s Cornell Food Venture Center discusses how soy sauce and fish sauce have “water activity” that are controlled, meaning that the water in the liquid condiments are very well bound to salt and other molecules.
The result is this: there’s little opportunity for pathogens to proliferate. So yes, you can keep fish sauce at room temperature without bacterial harm.
But just because you can do something, is it wise to always follow that rule? I do not.
Why Refrigerate Fish Sauce
To refrigerate fish sauce or not -- that’s a personal and functional choice. My 85-year-old mom doesn’t refrigerate nuoc mam. She blasts through fish sauce with all the Viet cooking that she does. She usually has two bottles open at a time -- a lesser quality one for cooking and a higher quality fish sauce for dipping sauces. That’s the typical, old-school Viet approach. Save the good stuff for the table.
I currently have 8 bottles open to develop recipes well, to provide fish sauce tastings in my classes, and just because I’m curious about different brands that I come across. I don't refrigerate them all.
Brands of fish sauce in my fridge include Son and Red Boat, Viet-made artisanal fish sauces that have high nitrogen levels -- a measurement of the condiment's umami intensity. A relatively high nitrogen level (“N”) means big flavor but it also makes fish sauces somewhat delicate. Left out at room temperature, those brands quickly develop gas inside their bottles. Open the cap and the fish sauce farts, which is somewhat alarming. I consider a fish sauce's gassy stability to decide if it needs to be refrigerated.
Danny Tran of Son Fish Sauce suggested refrigerating high-grade fish sauce to keep them better. He said finding a good cap for fish sauce bottles is a challenge. It needs to fit tight but people should be able to open a cap with relative easy.
Cuong Pham of Red Boat used to advise keeping fish sauce at room temperature but the RB label now says to refrigerate also. He’s also careful in sourcing the caps for his bottles. He mentioned that the caps Red Boat uses give a little but are strong and tight fitting.
My fridge door also has a supermarket fish sauce, made by A Taste of Thai. I like that fish sauce and though it’s not pricey and artisanal, I want to keep it for a long time so I may occasionally use it for recipe testing and take it to classes for nuoc mam tastings. It’s a brand that’s carried at at only a handful of supermarkets so replacing it is hard. I’d rather keep it in a safe place -- the fridge.
Another reason to refrigerate fish sauce -- if the briny savory fragrance gets to you, keeping nuoc mam/nam pla/patis chilled mitigates the odor. Note that high quality fish sauce is heady like dried porcini mushroom. Chill fish sauce to downplay its aroma.
What happens if you don’t refrigerate fish sauce?
There may be gassiness as mentioned earlier. Some fish sauce have preservatives like sodium benzoate so they don’t need to be stored in a chilly environment.
A popular brand like Megachef has a sleeve that nearly covers the entire bottle, as seen above. The purpose is to keep the fish sauce away from light and thus, from degrading, one of its distributors told me years ago. He told me that the packaging is designed for keeping fish sauce at room temperature.
Viet Huong’s Three Crabs doesn't have a nearly full sleeve label like Megachef does but I store the crabby one at room temperature too. Three Crabs contains fructose, as does Megachef, so I wonder if sweetener factors into the stability of the condiment. By comparison, Red Boat and Son are unadulterated fish sauces. I use Megachef and Three Crabs regularly for recipe development just like I would Red Boat, so I keep the former in my kitchen's condiment cabinet (as seen below).
With fish sauce that I don’t use as often, such as Megachef Brown label Fish Sauce, blended for Thai cooking -- I keep those in the pantry/closet, which is dark and cool in our Northern California climate. Note the vegetarian fish sauces in there too. They have a preservative. As you can see here, my pantry/closet is dark.
What if Fish Sauce Darkens or Salt Crystals form?
Salt crystals may form in bottles of fish sauce like Red Boat or Son, even when kept refrigerated. I used to be concerned about them but it’s a natural occurrence, Danny and Cuong have both told me.
If the fish sauce darkens in color or intensify in flavor, it has aged a bit. If that happens, just use a little less than usual in your cooking.
In summary, whether you refrigerate fish sauce or not depends on the brand, your frequency of fish sauce use, and how long you want to keep it around.
Regardless of how you store fish sauce, remember this: Make sure to close that cap after dispensing the fish sauce. Glance at the cap after measure nuoc mam and if needed, giving the top a quick wipe to avoid fish sauce crud build up that may prevent the cap from closing all the way.
If you keep your fish sauce at room temperature and it gives a little gassy “ooooph” when you open the bottle, I’d move it to the fridge.
How do you store your fish sauce?
Related articles
My recent articles at the LA Times
- From the Motherland to the U.S., a Vietnamese Fish Sauce with Umami Oomph ( a profile I wrote of the millenials making fish sauce in VN)
- Bun Ca Kien Giang Recipe (Fish and Shrimp Rice Noodle Soup; Kien Giang is a province renowned for fish sauce)
Robert Fox says
Your refrigerator door looks alot like mine, LOL. I have 2 bottles of Red Boat, one open in the fridge and one unopened in the pantry. The Red Boat says refrigerate after opening. I have always thought to refrigerate fish sauce, but then I thought of the Red Boat video of how it is made and aged. Hmmm. Your articles are the most informative out there. Thanks.
Jane says
As a thai, the popular brand that we use are either Tipparos(which i cant find here in montreal,canada) or Squid.
And we never refrigerate fish sauce and it last 1-3years per bottle for me. It certainly becomes crytalize at the bottom but the taste is still the same.
I only refrigerate oyster sauce as it coul be mold over time outside the fridge. It happen to me once though i use it very often,,
Andrea Nguyen says
Tiparos is not allowed into the U.S. anymore. Megachef is made by the son of Squid!
Thanks for sharing your insights, Jane.
Donald Nealious says
We refrigerated the first bottle we ever bought, and it crystalized. So we no longer put it in the fridge.
Andrea Nguyen says
There you go! You made your own choice. That's the way to do it.