Rinse the fish steaks and pat dry with a kitchen towel.
In a shallow pan (large enough to hold the fish steaks in a single layer), stir together the white sugar and two tablespoons coconut juice. Bring to the boil and cook until thickened and amber colored.
Stir the dark brown sugar and fish sauce into the caramelized sugar.
Arrange the fish steaks in a single layer in the pan with the sauce.
Pour in the rest of the coconut water. Sprinkle in the sliced ginger and chili.
When the sauce is simmering, cover the pan, set the heat to low and let the fish cook for about five minutes. Turn the fish over and cook for another four to five minutes.
Scoop out the fish steaks and transfer to a bowl.
Continue to boil the sauce over medium heat until thick and syrupy.
Pour the sauce over the fish steaks.
Garnish the Vietnamese-style catfish braised in caramel sauce with sliced scallions and chili before serving.