In Italy there are all sorts of combinations for fish soup: in fact every region has its own recipe. Always remember that if the fish is good and the cook is skilled, your fish will always be exquisite.
In the town Civitavecchia various types of fish are cooked such as the sargo, rockfish, smooth hound, squill, mussels and cocksfoot; less used but still very good is a type of murex fish.