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 For modern fish sauces, fish or shellfish is mixed with salt at a concentration of 10% to 30%. It is then sealed in a closed container for up to two years. Once the original draft has been made, some fish sauces will be produced through a re-extraction of the fish mass via boiling. To improve the visual appearance and add taste, second-pass fish sauces often have added caramel, molasses, or roasted rice. They are thinner, and less costly. Some volume manufacturers of fish sauce will also water down a first-press to manufacture more product. Fish sauce that has been only