I am a great believer in fresh stock made from natural ingredients.
It’s is far superior to prepared and processed cubes or tinned broths, which introduce too much salt and a chemical taste that has no place in a fresh soup. Making stock is essential in Moscow as there really is no acceptable commercial substitute. If you are going to the trouble of making it, do make a lot, and then freeze it in small batches so you have it handy.
For great fish stock, you will need some fish heads. Ask the guys at the market to give you the heads after they clean the fish, or ask them if they have some trimmings from cleaning other fish. Be sure to remove the eyes and the gills.
I keep a trimmings bag in my freezer in which I put all the tops and tails of vegetables and herbs. I dump this into the stockpot and the trimmings infuse a marvelous flavor.
If you are making a clear soup, you may want to take the time to clarify the stock. It’s a little bit of a slog, but I find it curiously satisfying and certainly nothing looks better than a clear, sparkling broth to showcase clear soup ingredients, set off by a brilliant green garnish.
Julia taught me how to do this. (Mastering The Art of French Cooking by Julia Child and Simone Beck.)