White fish fillet (e.g., cod): 150 g (5 oz), Potatoes: 150 g (1.5 cups, diced), Onion: 50 g (1/2 cup, chopped), Celery: 50 g (1/2 cup, diced), Milk (low-fat): 250 ml (1 cup), Olive oil: 5 g (1 tsp), Fresh parsley: 5 g (1 tbsp, chopped), Salt & pepper: To taste