Add the celery, garlic, onion, and pepper flakes and cook until translucent, about 6 to 8 minutes. Add the tomato sauce, wine and tomatoes and bring to a boil. Add the fish, and shellfish, cover and bring to a boil. Uncover and reduce the heat to a simmer until the shellfish have opened, 5 to 6 minutes.
Toast the bread and, while still hot, rub with the garlic. Lay 1 slice in each of 4 bowls. Divide the seafood among the 4 bowls, then divide the broth among the bowls, and sprinkle each bowl with parsley. Garnish with marjoram leaves. Serve immediately.