How to Make It
Melt the butter in a large saucepan. Add the celery, onions, carrots, bay leaves, thyme, parsley and peppercorns to the saucepan and cook over moderate heat, stirring occasionally, until the vegetables are softened, about 8 minutes. Stir in the fish bones, heads and trimmings and the wine. Cover and cook, stirring once, until the bones turn completely white, about 15 minutes.
Add the hot water, stir gently and bring to a simmer over high heat. Reduce the heat to low and simmer gently for 10 minutes. Remove from the heat, stir once and let stand for 10 minutes. Strain the stock through a fine sieve. Season lightly with salt and let cool, then refrigerate.