Preheat the oven to its highest setting.
Place the onion, garlic, 75ml/2½fl oz of the olive oil, the fennel, fennel seeds, star anise and half of the white wine into a large ovenproof casserole. Stir well then cook in the oven for 5-6 minutes, or until the vegetables have just softened.
Stir the tomatoes and crabmeat into the casserole and return to the oven for a further 4-5 minutes.
Meanwhile, scatter the cubes of bread into a roasting tray and drizzle with the remaining oil, mixing well to coat the bread.
Remove the casserole from the oven and add the croutons, toasting for 2-3 minutes until just browned.
Stir the lobster meat, pollock, mackerel, prawns and mussels into the casserole and season well with pepper. Remove the croutons and return the casserole to the oven for a further 8-10 minutes, or until the fish is cooked through (discard any mussels that remain closed).
To serve, sprinkle the croutons over the shellfish stew, garnish with the basil, then serve at the table with crusty bread.