Made from salted fermented fish, fish sauce is staple ingredient for seasoning in in many Southeast Asian cuisines. A whiff from the bottle reveals its pungent aroma and alludes to its very distinct, very potent taste. When combined with other ingredients like sugar and fresh herbs, the sharpness of fish sauce mellows out, its deeply savory side emerges, and its ability to add a lush umami-richness to everything it touches becomes apparent. What's important to know is that not all fish sauce is created equal; this condiment has distinguishing characteristics that can vary from region to region.
Origin Accounts for a Difference in Taste
Most Southeast Asian countries have their own version of fish sauce, although the Thai and Vietnamese varieties are the ones we tend to see on the shelves and use most often. While the process for making each one is similar, these two fish sauce varieties are set apart by their flavor and level of saltiness.
More About Thai Fish Sauce
Known as nam pla in Thai, this name literally translates into "fish water." Thai fish sauce is amber in color, and is known for having a saltier and more pungent flavor than its Vietnamese counterpart. It's typically produced using small ocean fish, namely anchovies, and salt and fermented over a period of time. But depending on the brand, it may also include sardines, mackerel, herring, or carp, as well as other ingredients like sugar or preservatives. Popular brands of Thai fish sauce include Golden Boy, MegaChef, and Squid.
More About Vietnamese Fish Sauce
Although still salty, nuoc mam, or Vietnamese fish sauce, has a lighter taste than its Thai counterpart. The best-quality nuoc mam is made with two ingredients: anchovies and salt. However, as with Thai fish sauce, this can vary between brands, and some may include other types of fish or additives, like sugar or preservatives.
Arguably the best Vietnamese fish sauce comes from Phu Quoc, an island off the southwest coast of Vietnam. The coastal waters are home to ca com, a variety of anchovy that makes for a delicately flavored, well-balanced fish sauce.
Take a look at the label; some brands of Vietnamese fish sauce also indicate the level of nitrogen, as noted in degrees N (such as 30°N, 40°N, etc.). This is a standard measure that indicates the grams of nitrogen per liter of fish sauce, with a higher number indicating a higher quality. Popular brands of Vietnamese fish sauce include Red Boat and 3 Crabs.
Read More: How Fish Sauce Is Made in Vietnam
Choosing Which One to Use
Despite their slight differences in flavor, Thai and Vietnamese fish sauces can be used interchangeably without significantly affecting the outcome of a dish. It really comes down to personal preference. If you're just starting to get acquainted with fish sauce, you're not likely going to notice a difference between using one variety over the other. On the other hand, if you're a fish sauce aficionado with a real taste for Southeast Asian cuisine, you might notice a small difference when using one for the other.
When swapping Thai fish sauce into a Vietnamese recipe, you may notice a slightly saltier outcome, and if you substitute Vietnamese fish sauce in a Thai recipe, you may feel like a little something is missing. But if you notice a difference at all, it's not one that will ultimately affect the taste of your meal. Where you're likely to find the most significant differences in flavor and quality is between different brands of fish sauce.