Essential ingredient for stocks and soups Choose heads/claws or tail shells Choose 1kg or 5kg packs - via More Options drop-down If you\'re looking to make a your own fish stock or shellfish bisque, these are a wonderful starting point. Just boil and strain. I\'m not quite sure what umami is, but apparently this gives you it in spades. Here\'s a lady who really takes her prawn shells very seriously , including processing the heads in her pestle and mortar. And her trash never smells fishy! This five minute video is well worth watching the whole way through. Well done Somjit.