Warm 2 tablespoons of the olive oil in a large soup pot over medium high heat. Add the onions, carrots, celery and fennel and cook until the vegetables are soft, 10 minutes.
Add the garlic, tomato, oregano, lemon peel, fish bones, white wine and 8 cups of water. Bring to a boil, reduce the heat and simmer, uncovered, for 40 minutes.
Periodically during the cooking time, with a wooden spoon, crack and mash the fish bones.
Remove from the heat and let cool. Strain broth, pressing on the bones to release as much of the liquid as possible. Discard the solids and place the broth back in a clean soup pot.
Heat the remaining 2 tablespoon of olive oil in a frying pan over medium heat. Add the garlic and Aleppo pepper and cook, stirring, until the garlic is soft, 3 minutes. Set aside. Bring the fish stock to a boil over high heat. Reduce to medium, add the potatoes and cook until almost tender, 8 to 10 minutes. Add the clams and simmer until they begin to open, about 5 minutes. Add the sea bass and monkfish and cook until the fish is opaque, about 4 to 5 minutes. Season with salt and lemon juice.
Ladle soup into bowls and drizzle the Aleppo/garlic oil onto the top.