Select a container which fits the size of the fish but not much more (the liquid needs to come into contact with as much of the fish as possible to cook evenly and infuse flavour). Place in the container the olive oil and heat over medium heat.
When the oil is hot, add the garlic and cook for 1-2 minutes until fragrant but not coloured.
Add the tomatoes, parsley, chilli, water, 1 teaspoon of salt and freshly ground black pepper to taste. Bring the mixture to a simmer.
Add the fish and cover.
Cook for 10 to 15 minutes until the thickest part of the fish can be easily pierced. Baste the fish twice during cooking. Place the fish on a serving platter, cover with the sauce and serve.
The fish can be served with bruschetta (grilled bread which has been drizzled with olive oil and sprinkled with salt).