Fish sauce is the salting agent most commonly used in Southeast Asia. For Thai people, it's one we use most commonly use in our cooking. Apart from being very salty it is also full of umami, and of course, a fishy flavour that doesn't smell good but tastes amazing.

The purest form of fish sauce only contains two things: anchovies and salt. But most brands will also add water, and also sugar to help balance the saltiness. Some low quality fish sauce brands also add flavour enhancers and food colouring to make up for the lack of actual fish in it.

Anchovies and salt are left to sit together for 12-24 months, and the naturally existing enzymes in the fish starts the fermentation and breaking down the fish. This results in a salty, flavourful, umami-rich liquid that can be considered the "first press" or the "extra virgin" fish sauce (not official terminology!).

Most fish sauce you can buy, however, is not virgin. (Red Boat is the only brand I know that is.) Most manufacturers will drain this liquid and then add more salt and water to the same fish to get a more diluted "second round" out of it. They can keep going a few more times (I'm not sure how many times they can keep doing this before the fish has nothing more to give.)

THEN they combine the first press with subsequent, more diluted presses according to their own recipe, plus sugar and whatever other ingredients they want to add. How much of the first press they use then determines the final quality of the fish sauce.

There are a few clues:
1. Ingredient list —the fewer ingredients the better. The best fish sauce only has fish and salt. Most common ones will also have sugar and water in addition, and this is totally acceptable. If there are more ingredients than these, it's not a good sign.
2. Protein content. The higher the amount of protein, the more actual fish is in it. A sigh of higher amount of the "virgin" fish sauce.
3. Price . Good fish sauce is more expensive to produce, so if it's super cheap, it's likely not great.

For this, you've got to watch the video below for the fish sauce tasting! But my recommended premium fish sauce is Red Boat, and Squid or 3 Crabs are good for everyday cooking. Check them all out at my recommended product listing page here.

Fish sauce will not spoil when left at room temp because of the high salt content, but to preserve the flavour, it's best to keep it refrigerated.

You can buy " vegan fish sauce " out there on the market, and there are some recipes for a homemade versions, such as this one by Andrea Nguyen , but generally soy sauce works perfectly fine if you don't want to buy or make anything. It's a different flavour, but it will still give you the salty umami that fish sauce has. In Thailand, most vegans and vegetarians use our various types of soy-based seasonings.

In Thai cuisine, fish sauce is used in everything: soups, salads, curries, stir-fries, dipping sauces, you name it! It is our default salt, but we also often use it in combination with soy sauce, oyster sauce, and fermented soybean paste.

If you're just getting started with fish sauce, first try some traditional dishes that typically contains fish sauce like a Thai papaya salad, pad thai , or tom yum soup.

Once you get the hang of it, and are familiar with how it tastes and how much to use, then you can start adding it to non-Thai dishes. It tastes great in chili or bolognese sauce for example!