Preheat the oven to its highest setting.
Combine onion, garlic, 75ml olive oil, fennel, fennel seeds, star anise, and 150ml white wine in a casserole.
Bake the vegetable mixture in the oven for 5 to 6 minutes until softened.
Stir in the tomatoes and crabmeat and bake for another 4 to 5 minutes.
Coat sourdough cubes with remaining olive oil in a roasting tray.
Place the bread in the oven for 2 to 3 minutes until browned to make croutons.
Remove the croutons and stir lobster, pollock, mackerel, prawns, and mussels into the casserole.
Season with pepper and bake for 8 to 10 minutes until the fish is cooked and mussels open.
Top the stew with croutons and basil and serve with crusty bread.