Pat the snapper dry with paper towels. In a skillet large enough to hold the snapper in one layer combine the horseradish, the ginger root, the tamari , the wine, and the white part of the scallions, add the snapper, and let it marinate for 30 minutes. Bring the mixture to a simmer over moderate heat and simmer the snapper for 4 to 5 minutes, or until it is just cooked through. Divide the pasta among 3 heated pasta bowls and transfer the snapper carefully with a slotted spatula to the bowls. Spoon the sauce over the snapper and sprinkle the snapper with the scallion greens. Serves 3. fish 13