Preheat oven to 425°.
Wrap 4 strips of bacon around the fleshiest part of each fish, 1/2 inch apart.
Tuck the garlic and thyme evenly under the bacon slices. If necessary, secure the bacon with wooden toothpicks previously soaked in water (about 30 minutes) to prevent their burning. Place fish in a baking pan. Surround with the potatoes and onions and add the water.
Roast the fish about 28 minutes. Turn, using 2 spatulas, being careful not to tear the skin, and roast for 2 minutes more. The fish is done when a metal skewer inserted into the thickest part of the flesh comes out warm to the touch. If necessary, add more water to the baking pan if it becomes dry before the fish is cooked.
Transfer the fish to a serving platter and surround with the vegetables. Spoon the pan juices over all and serve.