Heat the oil in a 4-quart soup pot set over medium heat. Add the shallots, celery, carrots, fennel, and potato. Cook 10 minutes, or until soft. Stir in the garlic; cook 1 minute. Deglaze the pot with the wine.
Add the fish stock, tomatoes, thyme, bay leaf, and orange zest. Bring to a simmer and let cook 30 minutes. Season to taste with salt and pepper (the amount of salt needed will vary depending on your stock.)
Add the shellfish and parsley. Cook, stirring occasionally until the fish is cooked through, about 10 minutes.
Remove the bay leaf and serve with garlic toasts.[br]