For the sauce
Cook the catfish in water and remove flesh. Fry the finely chopped onion and garlic in the butter; add the fish flesh, splash with the white wine, add salt and pepper to taste. Cook slowly for about 20 minutes.
Put the water on to boil with the stock cubes and some sea salt. When the water is boiling, pour in the rice and cook for about 15 minutes (very soft). When the rice is cooked, add the sauce and stir well for one minute. Serve and taste immediately.