Place fish in a large ceramic dish and toss with lime juice and 1 teaspoon salt. Chill for 30 minutes to marinate.
Meanwhile, heat olive oil in a large saucepan over medium heat. Cook onions until softened.
Add capsicum, garlic and chilli, then cook, stirring occasionally,until capsicum is softened.
Stir in stock/water, tomatoes, coconut milk. Bring to the boil, then reduce heat to medium and cook for 20 minutes until slightly reduced.
Add prawns, fish and marinating juices, then cook for a further 8-10 minutes until the seafood is just cooked. Add a little more lime juice on top and sprinkle with coriander leaves before servings.
Tastes great with rice.