This Classic Fish Chowder is an essential recipe you need to have in your repertoire. Once you have the recipe for the chowder base you can use different fish or seafood to complete the dish. You could easily make this a clam chowder. Add a little celery when you sauté the onions, use clam juice instead of the fish stock, finish with some cooked and diced salt pork for garnish and you'll have the perfect clam chowder.