Heat olive oil in a large heavy-bottomed pot over medium heat.
Add sliced onions and sauté until soft and translucent, about 5 minutes.
Stir in minced garlic, fennel seeds, thyme, and bay leaves; cook for another minute until fragrant.
Pour in clam juice and diced tomatoes, then add saffron threads and orange zest.
Season the broth with salt and black pepper to taste.
Bring the mixture to a gentle simmer and let cook uncovered for 15 minutes to develop flavors.
Add lobster tails to the pot and simmer for 8 minutes.
Add cod, halibut, and scallops; gently simmer for another 7–8 minutes, until all seafood is cooked through and tender.
Remove bay leaves and adjust seasoning if needed.
Serve hot with crusty bread on the side to soak up the flavorful broth.