Step 1Cook the onion and celery in the butter over medium heat until tender. Add the flour and stir to mix well, about 1 1/2 minutes. Add the potatoes, milk, reserved clam juice, half the parsley and salt and pepper to taste. Cover, bring to a boil. Simmer until the potatoes are tender, 10 minutes.
Step 2Add the chopped clams and fish and cook until the fish is tender, 10 minutes. Add the whipping cream. Bring the chowder to a boil, reduce the heat and simmer 10 minutes longer. Adjust seasoning. Add the remaining parsley and stir well.