Even if oysters aren’t fish, strictly speaking, they’re still shellfish and they still live in the sea. Given this, it’s not all that surprising that some people might be confused about the difference between oyster sauce and fish sauce.
Nevertheless, be assured that they are very different. In this article, we’ll explain what makes them different, what they’re both used for, and their origins and histories.
What Is Oyster Sauce?
To put it simply, oyster sauce is a sauce made of oysters. Sure, but that’s obvious. More specifically, it’s a sauce made by cooking oysters, reducing the resulting oyster water, and (usually) mixing it with other ingredients like sugar and corn starch to thicken it.
The result is a thick, dark brown sauce that has a rich, salty, umami flavor. It originated in China, and is widely used in Chinese cuisine, as well as the cuisines of other East Asian and Southeast Asian countries like Thailand, Malaysia, Vietnam, and others.
It’s loved for its ability to add a delicious savory kick to various kinds of dishes. In particular, it’s often used in stir-fried dishes. Just a few dishes that feature oyster sauce as an ingredient are: many versions of fried noodles, fried gai lan, and cold silken tofu.
It might seem like a contradiction in terms, but these days, there is such a thing is vegetarian oyster sauce. Of course, it doesn’t actually contain any oyster, but instead tries to mimic the taste of oyster sauce without animal products.
One of the most common ways to do this is to use mushrooms (usually oyster and/or shiitake mushrooms) as the base instead, though these sauces often contain higher amounts of flavor enhancers than regular oyster sauce.
What Is Fish Sauce?
As you’ve probably guessed, fish sauce is made from fish. There’s more to it than that, though! We’ll start off with a similarity between fish sauce and oyster sauce – both of them are widely used in Asian cuisine.
Fish sauce is particularly common in Southeast Asia, though it’s used in Chinese cooking as well. While oyster sauce doesn’t really have a specific oyster taste, fish sauce does smell and taste recognizably fishy, as well as being very salty.
It’s made by a process of fermentation in which the fish and salt are mixed and left to ferment for at least 3 months, and sometimes as long as a year.
While this is happening, bacteria are breaking down the fish into a brown, fishy liquid – fish sauce. Although it tastes very strong by itself, the flavor mellows out when it’s mixed with other ingredients and fades into the background to provide a pleasant umami boost.
There are actually several different kinds of fish sauce, and the variety common in Thailand, for example, might be noticeably different from the one you might see in Vietnam.
Thai fish sauce is known for having a stronger and saltier taste than its Vietnamese counterpart, with the Vietnamese version being lighter. That being said, the exact flavor can vary between different brands, even within the same country.
It’s usually not that important which one you choose to use, unless you’re a real aficionado who can notice the differences in flavor even after the fish sauce has been mixed with other ingredients.
Still, you might find that some recipes specifically recommend a particular kind of fish sauce.
The variety of fish sauce made in Laos, also called padaek, is a little different from its Thai and Vietnamese cousins. First of all, it’s made from freshwater fish rather than saltwater fish – a necessity since Laos is landlocked.
It is also thicker and more strongly flavored, and often contains actually chunks of fish as well, which msot other fish sauces do not.
Nevertheless, it’s used in many of the same ways in Laos as other Southeast Asian countries use their fish sauce (e.g. as an ingredient in green papaya salad).
Countries all over the region use it to add flavor to dishes like green papaya salad, larb, and pad Thai. It’s also used as a base ingredient for several different southeast Asian dipping sauces, usually supported by other ingredients like chili peppers and sugar.
However, fish sauce isn’t an entirely Asian phenomenon. The Ancient Greeks and Romans also made a kind of fish sauce, variously called garos, garum, or liquamen.
This was made by placing scraps from fish (usually the innards of mackerel) in a barrel with salt and leaving them outside in the hot Mediterranean sun for several months.
The resulting brown liquid would be strained and then used as a sauce. It was used on a wide variety of dishes and was also sometimes mixed with wine, honey, or vinegar.
After the liquid was extracted, the remaining fishy pulp (which the Romans called allec) was used by the poor, who couldn’t afford garum, to flavor their porridge.
Today, there is a very similar sauce called Colatura de Alici that’s part of the cuisine of Campania, Southern Italy. It is thought that this sauce is a direct descendant of garum, so if you’re interested in getting as close to the Ancient Roman sauce of choice as possible, that’s your best bet.
So, What Are The Differences Between The Two?
Oyster sauce and fish sauce are both salty, umamish sauces that are common in various Asian cuisines. That’s about where the similarities end.
Oyster sauce is much darker in color than fish sauce usually is. While oyster sauce is a dark brown, fish sauce is a lighter brown, amber kind of color, although this can vary with different kinds of fish sauce.
Nevertheless, it’s very unusual to encounter a fish sauce that’s as dark as oyster sauce.
The thickness is also a clear difference between the two; oyster sauce is much thicker fish sauce. Fish sauce has the consistency of water, while oyster sauce has a consistency more like thick honey.
The taste is different too. We’ve already said they’re both bring saltiness and umami, and that’s true, but they do it differently. With oyster sauce, the taste is heavier – almost meaty – whereas fish sauce does it in a lighter way.
You can also separate them by region. While all of them are used in Asia, oyster sauce originated in China, and reached Southeast Asia from there.
On the other hand, fish sauce was first popular in Southeast Asia, and from there reached China when it was brought there in the 17th and 18th centuries by Chinese merchants.
There you have it, the differences between oyster sauce and fish sauce. Both of these delicious types of sauce play an important role in the cuisines of the countries that use them to add flavor to all kinds of dishes.
If you haven’t tried cooking with them before, give them a go and taste the delicious results for yourself! It’s common for supermarkets to stock both kinds of sauce these days, but if your local one doesn’t have any, then any Asian supermarket should be able to hook you up.
Failing that, you can always buy online (where you’ll have a wide range of brands and styles to choose from.