Homemade broth is always better. Store-bought is more convenient, but whenever I give in and use it I feel like I’m cheating. And even so-called “plain” chicken broth has more ingredients than you can imagine, along with that puzzling term “other natural ingredients.”
Granted, not everyone agrees, and not everyone has time to keep a pot of chicken or beef broth simmering for hours (though I dare say it does most of the work itself).
Fish broth, however, is ready in practically no time, and it can even be free. Most fishmongers will gladly give you meaty bones, carcasses, cheeks and fish heads. Use bones from any white-fleshed fish. Rinse them well and put them in a soup pot (just a pound or so is plenty to make a light broth). Cover with 10 cups cold water, add a sliced onion or a few scallions and turn the heat to high. Don’t let it come to a boil. Keep it at a bare simmer for 30 minutes, then strain. You’re done.