Heat 2 tablespoons of the olive oil in a large saucepan and sauté the onion, fennel, garlic and fennel seeds for 4–5 minutes.
Stir in the chopped tomatoes and cook for a further 12–14 minutes, until the vegetables are tender.
Meanwhile, heat the remaining olive oil in a saucepan and cook the clams, covered, for 2–3 minutes, until they have all opened. Discard any clams that do not open.
Pour the stock and saffron into the tomato mixture and bring to the boil. Add the prawns, red mullet and monkfish and simmer for 5–6 minutes, until the fish is cooked through and the prawns turn pink. Add the cooked clams.
Stir through the chopped parsley and serve immediately.