Fish sauce are made with anchovies, mackerel, scabbard fish and salt. The bigger the fish, the more mercury you might expect, especially if predator fish like scabbard fish. They do not have any additives like sugar, hydrolyzed protein, or preservatives. Vietnamese prefer sauces without a strong smell, and transparent with a deep golden amber color. "First press" fish sauce, meaning the sauce is bottled from the first time the fermenting barrels are drained, also indicates quality. Lastly, when measuring the nitrogen level of fish sauces (N), most fish sauce on the market falls within the mid 20N range. Anything over 30N is
Fish sauce at the table as a condiment, for instance in noodle soups. Nearly every Thai meal is served with "phrik nam pla" as a condiment: a mixture of fish sauce, lime juice, and chopped bird's eye chilies. Sliced garlic and lemon juice are often added to this sauce. Historically, there were two types of fish sauce made in Thailand: that made with a fresh-water fish, "pla soi", and sauce made from a salt-water fish, "pla kratak". Either fish is fermented for at least eight months, three parts fish to two parts salt. The resulting mash is filtered. This yields the best