In addition to fish heads and tails, I put dried herbs (rosemary, thyme, small Basil), fresh coriander and dill in the broth,:one onion, Bay leaf and a piece of leek. Salt and pepper. I froze a liter of broth for Fideua, and made fish soup out of the rest. If you cook broth and Fideua in one day, and there will be waste from the shrimp (I cook whole, but many people do not like it when they are served from a plate) they can also be used in broth