Scale, clean, filet and cut the scorpion fish into large pieces. Thinly slice the onion and garlic. Wash and quarter the tomatoes. Heat the oil in a pan over medium heat. Sauté the onion and garlic until golden brown. Add the tomatoes, basil and hot pepper. Cook until the tomatoes are soft.
Add the filets, seasoned with salt and pepper, and two tablespoons water.