In a large stockpot, combine 4 cups of water, 1/4 cup of sugar, and 2 tablespoons of salt. Stir until dissolved and bring to a rolling boil over medium-high heat.

Once the liquid reaches a boil, gently lower the firm white fish fillets into the pot. Reduce heat to a gentle simmer and cover. Allow to poach for 8-10 minutes, or until fish is cooked through.

Using a slotted spatula, remove the poached fish and place on a cutting board. Pat dry with a kitchen towel.

In a small saucepan, melt 4 tablespoons of butter over low heat. Brush it generously over the fish fillets.

For an extra texture, preheat the broiler to high, transfer fish onto a baking sheet, and broil for about 1 minute.

Transfer the broiled fish to a serving platter and serve warm, optionally with additional melted butter on the side.