Hey there, I’m Mia, and I’ve been in the soy sauce game for 8 years now – first helping my dad run our small soy sauce brewery, now as part of our team that works with all kinds of home cooks, line cooks, and even restaurant owners testing recipe swaps. The question I get more than any other lately? “Can I replace fish sauce with soy sauce?” It makes total sense, right? Fish sauce isn’t cheap, it has that super distinct salty, funky, umami kick that not everyone loves, and sometimes you just run out mid-stir-fry or don’t want to open a bottle you’ll use once a year. I’ve had every version of this question: from a college kid making pad thai in a dorm microwave to a family friend testing her grandma’s Thai curry recipe and panicking because she forgot to grab fish sauce at the store. Let’s break this down like we’re chatting over a cup of jasmine tea – no stuffy food science jargon, just real talk about what each sauce does, when a swap works, when it doesn’t, and why our soy sauce is actually a pretty solid alternative (no bias, promise – just facts we’ve tested hundreds of times). Soy Sauce
First, let’s get the basics straight because so many people mix these two up, and it starts with how they’re made. Fish sauce is fermented from anchovies (or other small fish) and salt – that’s it, basically. It’s super concentrated, so a tiny drop packs a huge punch, and it has that briny, sometimes “fishy” note that’s both the star and the turn-off for some folks. Soy sauce, on the other hand, is fermented from soybeans (we use non-GMO ones in our brewery) and wheat, plus salt and a starter culture (that’s the mold that does the fermenting magic). That’s why our soy sauce has that rich, savory, slightly sweet depth – it’s not just salt, it’s got layers from the beans and wheat breaking down over months. Now, the key word here when it comes to replacing is umami. Both have umami, that fifth taste that makes food feel satisfying, not just salty. But their umami comes from different things, and their salt levels, flavor profiles, and textures are way different than most people realize.
Let’s talk about when this swap works first, because that’s the stuff most home cooks care about. I once watched my little cousin make chicken pad thai with our light soy sauce instead of fish sauce, and it turned out better than the original she’d made with fish sauce before – but only because she adjusted the amount, not because she just poured it in equal parts. Here’s the rule of thumb we tell everyone at our brewery: when a recipe calls for fish sauce and you don’t mind losing that tiny briny kick, light soy sauce (that’s our thinner, more delicate one) works great for things where you want to keep the salty, savory boost without extra funk. Think dressings, marinades for chicken or pork, stir-fries where the other flavors are strong (like garlic and ginger dominating), or even dipping sauces for dumplings. We tested this last month with a local restaurant that was cutting back on fish sauce for customers who hate fishy tastes – they swapped 1:1 light soy, added a tiny bit of sugar to round it out, and their new menu item outsold the old one by 20% in the first two weeks. That’s real.
But wait, there’s a catch with the amount. Fish sauce is way more intense than most people think. Let’s say a recipe calls for 1 tbsp of fish sauce – that’s not a lot, but because it’s concentrated, you only need 1/2 to 3/4 tbsp of light soy sauce to get the same saltiness and umami. If you just pour 1 tbsp straight in, it’s going to be too salty, and the flavor might be too plain because light soy doesn’t have that extra fishy depth. Also, if the recipe has other bold flavors, like lime juice, chili, or coconut milk, the soy sauce’s milder profile fits right in. I made a Thai-style coconut curry last weekend for my mom, who’s allergic to fish, and used our dark soy sauce (the thicker, more robust one) instead of fish sauce – it worked perfectly, because the coconut milk and spices masked the fact that we didn’t have fish sauce. Dark soy has a deeper, maltier flavor, so it’s better for heartier dishes where you want the sauce to hold its own.
Now, when this swap doesn’t work – and I don’t want you to waste a good dish thinking it’ll work everywhere. The biggest one? Any recipe where that fishy, briny kick is the star. Like traditional nam prik, that spicy Thai chili paste that relies entirely on fish sauce for its flavor, or a Vietnamese fish sauce dip (nuoc cham) that’s supposed to have that distinct fishy tang. If you replace fish sauce with soy sauce there, it’ll taste like salty soy with chili and lime, and it’ll be missing that key layer that makes it authentic. I learned this the hard way – my first year brewing soy sauce, I tried to make nuoc cham for a friend’s taco night and used light soy, and she laughed and said it tasted like “soy sauce with a side of regret.” Oops. Also, if you’re making a dish where you don’t want a darker color – like a light, bright pad thai, a salad dressing, or a pickling brine – dark soy sauce will turn it brown, which messes up the look as well as the flavor. I once had a home baker email me panicking because she used soy sauce instead of fish sauce in a pickled vegetable recipe, and all her veggies turned a weird murky brown instead of bright green. So color is a big one too.
Wait, let’s get into the science a little, because I know some of you are like me – I need to know why something works, not just that it does. Fish sauce’s umami comes mostly from amino acids like glutamate, but also from that histamine from fermented fish, which gives it that sharp, briny note. Our soy sauce’s umami comes from glutamate (way more of it, actually – fun fact: our regular soy sauce has about 1,600 mg of glutamate per 100ml, while fish sauce has around 1,200 mg) and other compounds from the fermented soybeans and wheat, like aspartate and guanylate, which give it that smooth, savory depth. That’s why when you adjust the amount, the umami is there, but the flavor is different. Fish sauce also has a lower sodium content, actually – around 1,800 mg per tsp, vs our light soy sauce’s 2,000 mg per tsp. So the salt difference is small, but the overall flavor intensity is big, which is why you need less soy sauce. A lot of people think soy sauce is way saltier, but it’s only slightly higher – the issue is the flavor concentration, not the sodium.
Now, what about other types of soy sauce, not just light or dark? Like low-sodium soy sauce? That’s a trickier swap, because low-sodium has less salt, so it won’t give you that same salty kick as fish sauce, and it might taste flat. If you only have low-sodium soy and need to swap, use a little more (like 1.5 tbsp for 1 tbsp of fish sauce) and add a tiny pinch of salt, but just a pinch – don’t overdo it. And what about tamari? A lot of people confuse tamari with soy sauce. Tamari is a Japanese-style soy sauce, made with little to no wheat, so it’s thicker and richer. That works as a swap too, but it’s even more intense, so use even less – like 1/3 to 1/2 tbsp for 1 tbsp of fish sauce. We make a small batch of artisanal tamari at our brewery, actually, and a local sushi chef uses it to replace fish sauce in some of his rolls because it adds that rich depth without the fishiness.
I also want to talk about common mistakes people make when doing this swap, because I’ve seen them all. First, not adjusting the amount. Like I said, fish sauce is concentrated, so don’t do equal parts. Second, not adding a little sweetness if you can. Most fish sauces have a hint of natural sweetness from the fermented fish, so adding a tiny bit of sugar (like 1/4 tsp per tbsp of soy sauce) helps balance the soy sauce’s savory flavor. Third, using the wrong type of soy sauce for the dish. Light for light dishes, dark for hearty ones – don’t use dark soy in a pickling brine, or light soy in a braised pork dish, because it’ll get lost. I once had a home cook email me saying her stir-fry tasted “boring” and it turned out she used light soy in a dish with lots of oyster sauce and mushrooms – we suggested swapping to dark soy, and she said it was like adding a whole new layer of flavor.
Here’s the thing, though: at the end of the day, this is a swap that works for convenience, for dietary needs (like my cousin, who’s allergic to fish), or just because you don’t like the fishy taste. It’s not a 1:1 perfect replacement for every single recipe, but that’s okay. Most swaps aren’t – cooking is about making things work for you, right? I’m all for using traditional ingredients when you can, but life happens. You run out, you have dietary restrictions, you don’t want that funky taste. Our soy sauce is designed to be versatile, so it fits into all kinds of dishes, including as a fish sauce substitute when you need it.
If you’re a food service operator, a restaurant owner, or even a home cook who uses a lot of both sauces, let’s chat. We’ve got different types of soy sauce for every use – light for stir-fries and dressings, dark for braises and marinades, low-sodium for people watching their salt, and even artisanal small-batch ones for when you want that extra depth. We can help you figure out exactly how much to use for your recipes, whether you’re swapping fish sauce or just looking for a better soy sauce to stock in your kitchen. No sales pitch, just real answers because we’ve been doing this for years and we know how frustrating it is when a swap goes wrong.
Wait, one last quick tip I learned last month: if you’re making a dish where you really want that subtle briny kick but don’t have fish sauce, mix a tiny bit of our light soy sauce with a pinch of anchovy paste (not whole anchovies, just the paste) – that’s a middle ground if you want to keep that fishy note but don’t have the bottle. But if you’re okay without that, straight soy sauce with a little sugar is perfect. I tested that on my roommate, who swears she hates fish sauce, and she couldn’t tell the difference in her weekly chicken stir-fry.
At the end of the day, the answer to “Can I replace fish sauce with soy sauce?” is: yes, if you do it right. It’s not a perfect swap for every recipe, but it works for most, especially when you adjust the amount and pick the right type of soy sauce for your dish. If you’re ever unsure, just hit us up – we’re always here to help, whether you need a quick tip for a dinner tonight or are looking to stock up for your restaurant. No question is too small, no swap is too weird. That’s what we do here.
Other Products References:
- Food and Agriculture Organization of the United Nations. Fermented Foods in Asia and the Pacific. 2018.
- Zhang, Y., et al. Umami Compounds in Soy Sauce and Fish Sauce: A Comparative Analysis. Journal of Food Science and Technology, vol. 52, no. 9, 2015, pp. 5681-5688.
- Lee, S. H. Traditional Southeast Asian Fermented Fish Products. CRC Press, 2003.
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