A little factoid, it is native to San Francisco, although it traces its roots back to both the Italian and Portuguese fisherman that worked the San Francisco Bay. Although it is usually seasoned with mussels and clams (which were very common in the docks back then) it only requires that it be the catch of the day, usually what was not sold, or sale-able. Most often, rock cod, clams, mussels, perch and occasionally squid are the base of the cioppino. The best places would add in baby octopus, Dungeness crab, even crayfish.
The biggest difference between this, and say a Bouillabaisse, Cuippine or Portuguese Fisherman's stew is the soup base. The Ligurian and Sicilian soups often use a fish broth base, and add just a little tomato. Bouillabaisse uses a lot more saffron and the Portuguese use things such as cumin, saffron, pepper and fish for the base. The typical San Francisco recipe is rich with tomato, garlic, bay and onion, as well as a seafood broth. I love this stuff, but, cannot eat it anymore, as my allergy to mussels has gotten to the point that even if the mussels are removed, the broth will cause BAD BAD issues
me: I don't drink anymore
Yelonutz: me either, but, then again, I don't drink any less