Heat half the olive oil and fry the fish and prawns until just-cooked. Remove and season well.
Add the remaining oil and fry the onion, celery, garlic and red pepper for 10 minutes, stirring well.
Add the tomatoes and stock, then bring to the boil.
Add the rice, paprika, bay leaves, salt and pepper, stirring well. Reduce the heat to very low, cover and simmer for 20 mins until the rice is cooked but still wet and soupy (add more stock or water if not).
Add the fish and prawns, then heat through for 5 minutes.
Scatter with parsley and serve in bowls, with lemon wedges.