Clean the fish and remove the internal organs. For grilling, it is best to pull out the internal organs by making a horizontal cut under the head, rather than opening the fish’s abdomen with a long incision.
Scrape the slime off the catfish skin with a knife. Rub the catfish with coarse salt, then wash it thoroughly.
Using a sharp knife, score the fish by making vertical cuts along its body, 2.5” (6 cm) apart.
Insert a bamboo skewer through the fish’s mouth going through the entire fish but not coming out at the end, leaving enough of the skewer to hold the fish.
Rub and marinate the fish for 20 minutes with thick dark soy sauce, light soy sauce, salt, ground white pepper, and bruised garlic.
Light up the charcoal, and wait until the flames subside; wait until the charcoal is properly heated up before starting the grilling process.
Place the catfish over the grill; if it flames, then the grill is probably too hot. Place some ash over the charcoals to reduce the heat.
The fish should be slowly grilled until its skin is crispy and shiny.