Fillet the fish and remove small bones using tweezers.
Roughly chop fish trimmings and heat olive oil in a large saucepan.
Fry fish trimmings for 10 minutes until brown and then set aside.
Fry shallot, fennel, tomatoes, garlic, and spices until vegetables soften.
Add trimmings and 2 liters of boiling water, then simmer for 35 minutes.
Strain the stock through a sieve into a clean pan and season.
Add potatoes to the stock and boil until nearly cooked.
Cut fillets into 5cm pieces and discard any damaged mussels.
Add seafood to the pan and simmer for 3 minutes until cooked.
Serve in bowls garnished with parsley and olive oil.