In a 3 to 4-quart stockpot, combine the fish bones, white wine, and just enough water to cover (you won't need the full quart of water here). Bring to a boil, skimming off the white foam from the top of the stock as it approaches boiling, then reduce the heat so the stock simmers. (Using a ladle and a circular motion, push the foam from the center to the outside of the pot, where it is easy to remove).
Add the onions, celery, carrots, bay leaves, parsley, thyme, and peppercorns and stir them into the liquid. If the ingredients are not covered by liquid, add a little more water. Allow the stock to simmer gently for 20 minutes.
Remove the stock from the stove, stir it again, and allow it to steep for 10 minutes. Strain through a fine-mesh strainer and season lightly with salt. If you are not going to be using the stock within the hour, chill it as quickly as possible. Cover the stock after it has completely cooled and keep refrigerated for up to 3 days, or freeze for up to 2 months.