When a bowl of fish becomes a meal

``A fine kettle of fish'' may not always be a complimentary phrase, but taken literally it signifies a wonderful addition to menus any time of year. The best thing about chowder for the cook is that it can be prepared ahead of time and makes a meal when served with a fresh salad, hot rolls or biscuits, and a country-style dessert.

Some say the word chowder originated when French fishermen from Newfoundland and Nova Scotia settled in New England and brought with them fish dishes called chaudi`eres.

Chaudi`ere is also the French word for a large cauldron. Years ago it was the custom of Breton sailors to combine their catch in a pot on the beach and make a community stew.

Just about any kind of seafood can be used for chowders, but underutilized species can make this an especially economical dish. Look for unfamiliar chowder fish in market display cases, or ask the seafood clerk which fish are good values.

Frozen fillets simplify preparation, although most seafood cooks insist that a fish with bones will provide more flavor. The main thing to remember is not to discard the bones if you have them. Poach them in water with a few onions and seasoning, then strain the liquid and use as a base for the chowder.

Salt pork, diced and saut'eed until golden brown, is also a part of traditional New England fish chowders, but bacon is often used as well as other variations.

``Shellfish such as scallops, shrimp, clams, oysters, and lobster will make a very elegant dish, and although they are usually expensive, the cost is minimal when used with other seafood in smaller amounts,'' says Gabrielle Nagy, a nutrition communication graduate student at Boston University and an intern with the Massachusetts Division of Marine Fisheries.

``For example, one pound of shellfish meat is all that's needed to make four generous bowls of chowder,'' she says. Pollock and Watercress Soup 1 pound pollock fillets (or any white fish fillets) 2 tablespoons margarine 1 small leek, chopped 1 small onion, chopped 1 bunch watercress, chopped 2 cups fish stock or bottled clam juice 2 cups chicken stock 1/4 pound potatoes, peeled and diced 1/2 cup or more half and half (milk and cream) Salt and pepper

Poach fish in enough water to cover and set aside when done. Saut'e leek, onion, and watercress in margarine. Stew at low heat for 10 minutes, stirring occasionally.

Add fish stock, chicken stock, and potatoes; cook for about 40 minutes.

Cool slightly. Cut pollock into small pieces and add to cooled mixture along with salt, pepper, and half and half. Garnish with watercress sprigs. Serve hot or cold. Makes 4 servings. Tomato and Cod Soup 1 pound cod fillets 1 can condensed tomato soup 1 8 1/4-ounce can sliced stewed tomatoes 3/4 cup water 1/2 teaspoon dried basil Dash pepper

Combine all ingredients except fish in a saucepan and bring to low simmer. Cut fish into small cubes and add. Continue simmering, stirring occasionally, until fish is cooked, 10 to 15 minutes. Makes 3 to 4 servings.