Homemade Fish Stock for Soup and Chowder

Remove the gills if using fish heads. Rinse the bones under cold water and cut them into pieces if needed to fit your pot. Soak the bones in cold water for 10 minutes, then drain.
Roughly chop onions, carrots, and celery, and garlic.
In a large stockpot, heat butter or oil over medium heat and sauté the vegetables for about five minutes until softened but not browned.
Add the fish bones to the pot and cook for another five minutes.
Pour in white wine letting it reduce by half, about 3 minutes.
Add the cold water, bay leaf, peppercorns, parsley or thyme, and a generous pinch of salt. The bones should be completely submerged.
Bring the mixture to a simmer uncovered over medium-high heat, then reduce to medium-low to maintain slight movement without boiling.
Skim any foam that rises to the surface. Let the stock simmer for 30 minutes.
Strain it through a fine mesh strainer and discard the solids.
Strain the stock into shallow containers or cool it rapidly in an ice bath. Refrigerate within 2 hours. Once chilled, skim off any hardened fat before using or freezing.