What keeps my homemade kimchi from spoiling ?

Just think of the art of Kimchi making as being in a laboratory for the afternoon. There are so many organic chemistry processes happening. Fish sauce is laden with tons of salt. So, that will act as a stablizer/preservative alone. (If you only knew how it is truly made)...trust me...a person would probably die before fish sauce truly goes bad. Then, the process of fermentation will release "lactic acid" and that acts like a stablizer/preservative too. There is a huge difference between fermentation & spoilage. One should not be confused with the other.