Nam Pla or Thai Fish Sauce is a seasoning sauce widely used in Thai and other Asian cuisines. Thai Fish Sauce is an absolutely indispensable ingredient in Thai cooking and is used instead of salt. Thai Fish Sauce is a brown, highly aromatic sauce made from fresh fish, mostly Anchovy but can be any fish.
Small fish that have little commercial value because of their size, are use to make Nam Pla and these tend to be saltwater fish which are plentiful rather than freshwater fish which in Thailand have become depleted.
Thai Fish Sauce is made by adding sea salt to the fresh fish which is then placed in sterilized tanks, loosely covered and then left to ferment and mature for about 1 year. The high salt content prevents the spread of bacteria in the tank. After this time the Fish Sauce has risen to the top of the tank and this is drained off and filtered to make premium grades of Nam Pla. Before bottling the Fish Sauce is usually filtered for a 2nd time, before adding sugar (about 1%). Lower grade Fish Sauce is made by adding salt water to the remains in these tanks and allowing to stand for about 3 months or so before being filtered, sugared and bottled. It takes about 5 lbs of Fresh fish to make 1 standard size bottle of Nam Pla.
Because the making of high quality Fish Sauce is a time consuming business, some of the lower grade Nam Pla is made by adding enzymes to the fish to speed up fermentation whilst others contain high amounts of Monosodium Glutamate (MSG) and use caramel for the colouring. Yet others will add lower grade Fish Sauce to the premium grade to increase the quantity.
As not all Nam Pla is the same, try to ensure that you purchase only premium grade Thai Fish Sauce. Reading the labels may help although this unfortunately is not foolproof, some being more fictional than factual. Good Fish Sauce should look clear and similar in colour to Scotch whisky, and not smell or taste too fishy. Try various brands until you find one that you like.