A recipe for Italian seafood soup is Food & Wine's Italian seafood stew. It calls for fennel, celery, onion, tomato puree and parsley as well as a variety of seafood, including squid, mussels, clams, shrimp and bass.
To make this soup, saute 1 finely chopped fennel bulb, 2 finely chopped celery ribs, 1 minced white onion, 1 tablespoon of dried Sicilian oregano and 1 pinch of crushed red pepper in 1/2 cup of extra-virgin olive oil at medium heat for 15 minutes, stirring often. Once the vegetables soften, turn the temperature to low, and add in 1 1/2 pounds of cut squid. After 15 minutes, add 2 cups of dry white wine, and increase the temperature to medium-high heat until the liquid boils off. Stir in 1 28-ounce can of tomato puree, strips of lemon zest from 1 lemon, and salt and pepper to taste, and cook the stew on low for 40 minutes.
Add 2 cups of water and 1 cup of bottled clam broth to the soup, and increase the heat until the liquid boils. Remove the lemon zest strips, season the soup with salt and pepper to taste, and stir in 12 ounces of mussels, 12 ounces of littleneck clams, 12 ounces of deveined large shrimp and 12 ounces of skinless and chopped striped bass fillet. While the seafood cooks through, toss grated lemon zest from 1 lemon and 2 tablespoons of minced flat-leaf parsley in a bowl. Serve the stew topped with the parsley mixture.