Heat the oil in a large stockpot over medium heat. Stir in the onion, celery, carrots, potatoes, and garlic, and cook 5 to 10 minutes. Add parsley, cilantro, tomatoes, tomato juice, clam juice, white wine, basil, oregano, thyme, chili powder, cayenne pepper, salt and black pepper. Reduce heat and simmer for 2 hours.
Approximately 15 to 20 minutes before you are ready to serve the cioppino, stir in the fish, shrimp, mussels, clams, crab, and scallops. Continue to cook and stir approximately 5 minutes, or until the shrimp are pink and the clams and mussel shells have opened. Remove any unopened mussels or clams before serving.