Ligurian Seafood Soup

Name: Ligurian Seafood Soup
Ingredients: 1/4 cup extra-virgin olive oil, plus more for serving; 1 large sweet onion, thinly sliced; 2 garlic cloves, thinly sliced; 1/4 cup finely chopped flat-leaf parsley; 1/2 teaspoon crushed red pepper; One 28-ounce can whole peeled Italian tomatoes, drained and chopped; 2 strips of orange zest (optional); Salt and freshly ground black pepper; Four 8-ounce skinless halibut or other meaty white fish fillets; 2 cups pitted green and black olives, such as picholine and kalamata (about 3/4 pound); 2 pounds large shrimp, shelled and deveined; 1 pound cleaned calamari, bodies cut into 1/2-inch rings; 20 littleneck clams, scrubbed; 1 pound mussels, scrubbed and debearded; 2 cups bottled clam juice; 1 cup dry white wine; Grilled bread, for serving (optional)