Salt cod -- which is salted and dried and must be rehydrated by soaking for 24 hours before cooking -- was invented hundreds of years ago as a method of preserving fish (and boosting its flavor). Dried salt cod can be safely stored in a refrigerator for 2 to 3 years in its original packaging, protected from heat and light.

If you purchase frozen salt cod -- which is salt cod that has been rehydrated and then frozen -- it can be held in the freezer for up to 1 year.