Place fish, lime juice and salt in a bowl. Marinate while you continue.
Heat the olive oil in a large fry pan and add the onion and garlic. Cook until the onion is softened. Add the marinated fish, tomato paste, water and simmer for about 10 minutes over medium heat, and the fish is cooked through.
Mix in the coconut milk, pepper sauce, parsley and simmer for another 5 minutes. This is good as a soup or served over white rice. You can also add shrimp, mussels, etc.