Mix peaches, red bell pepper, walnuts, green onions, lime juice, ginger and 1/8 tsp. salt, in a small bowl to blend. (Salsa can be made 2 hours ahead. Cover and refrigerate.)
Bring the 6 cups of water to a boil in a large saucepan. Lower fish into the pan, using a spatula or slotted spoon and bring the water back to a boil. Reduce the heat to very low, and poach the fish for 3 to 4 minutes or until it is just cooked through. Remove from water, using a slotted spoon or spatula.
Boil water and 1/8 tsp. salt in a medium saucepan. Stir in couscous and cover. Remove from heat and let sit for 5 minutes. Fluff with fork and add parsley before serving.
Serve each cod fillet with couscous and peach salsa.