How to Make Fish Stock
Use only fish from the sea, not from rivers and lakes. You can use anything you like. For example, you can use 1 pound of sardines and/or fish heads (say salmon, grouper, Mahi Mahi, shirimp, or the “skin” of the shrimp. Always use some, say 10 or so mussels or clams, etc. and their spines. Do not use small fish. Then, you do not have to deal with their small bones that will choke some guests not used to eating fish).
In a pot (really big), add the fish; it should occupy about 1/3 to ¼ of the pot. Add 1-2 glasses white wine –depending on how big your pot is, 1 red onion cut in 4, 4 cloves of garlic crushed, 1 bunch of parsley, 1 sprig of rosemary, 1 celery cut in pieces, water up to 2 inches to the top, black peppercorns, and salt. Let it boil lightly for 2-3 hours or three, until the water is about half then what you started with. Drain the broth, set aside until it reaches room temperature, and then freeze. When you need it, you will defrost it.