Anchovy fish sauce is an essential condiment along with shrimp fish sauce in making various types of kimchi to accelerate the fermentation process.
It is made from raw anchovies and coarse sea salt through fermentation. Some people (especially from southern part of Korea) use it to season blanched vegetables or soup as well.
Make sure the lid is tightly closed.
(Opened or unopened will not affect the flavor of the product but keeping it closed could prevent the smell from being too exposed out in the open.)
Keep in a cool and dry place.