For many single cooks, preparing a seafood meal means opening a can of tunafish. But such simplicity may have complex nutritional benefits. It's no news that fatty fish -- such as tuna, salmon, swordfish, mackerel and trout -- have become the most talked about seafood since blackened redfish.

Oily fish contain high levels of a polyunsaturated fatty acid called omega-3, which gets its name from its chemical structure (the first unsaturated bond is located between the third and fourth carbons). In the early 1970s, studies on populations that consume a diet rich in fatty fish -- such as Greenland Eskimos and Japanese fisherman -- showed a low incidence of coronary heart disease.

Then last May, three studies published in the New England Journal of Medicine came to similar conclusions about fatty fish and coronary heart disease, as well as their ability to lower serum cholesterol and lessen inflammatory conditions such as arthritis.

Since then, the subject has continued to be a hot research topic at universities, medical centers and government health agencies. Experts have only scratched the surface, however; there are still a lot of "mays" and caveats, such as the fact that industrial and agricultural chemicals found in polluted waters can accumulate in the tissues of fatty fish.

Scientific debate aside, eating fresh fish has at least three other benefits to the single cook. For one, fresh seafood counters are proliferating in area supermarkets, making it easy to pick up a fillet, a lemon and some broccoli and zoom through the express lane. For another, fish are fast food; they take -- at the most -- 10 minutes to cook. Ten minutes in the market and 10 minutes in the broiler is less time than it takes to heat a frozen dinner. But perhaps most importantly, seafood may be the ultimate portion control dinner for single cooks. Unlike a pack of ground beef or chicken, a can of beans or a head of lettuce, a fillet or fish steak can be eaten and finished in one sitting.

Here are some recipes that use fish high in omega-3 fatty acids, take no longer than 20 minutes for total preparation and cooking time and call for a minimum of ingredients and caloric additions. CARL'S DARKENED TUNA (1 serving)

1 1/2 tablespoons chili powder

1/2 teaspoon each cumin and oregano

1/4 teaspoon cayenne

4 to 6 ounces fresh tuna

Combine chili powder, cumin, oregano and cayenne. Dredge fish in spice mixture, shaking off excess. (Reserve for future use.) Heat nonstick pan over medium heat for about 2 minutes. Place fish in pan and cook over medium heat for about 10 minutes, flipping once. Serve immediately. BROILED LEMON-GINGER SWORDFISH (1 serving)

1 teaspoon grated fresh ginger

2 tablespoons lemon juice

2 teaspoons olive oil

4-to 6-ounce swordfish steak

Mix ginger, lemon juice and olive oil together. Brush over both sides of swordfish steak. Broil approximately 5 minutes per side, brushing periodically with lemon-ginger sauce. SALMONBURGERS (1 serving)

4 to 6 ounces fresh salmon

1/3 cup whole wheat bread crumbs

1/2 teaspoon grated lemon peel

1/4 teaspoon crushed rosemary

1/8 teaspoon freshly grated black pepper

1 tablespoon lemon juice

Kaiser roll, dijon mustard, sliced red onion and tomato for serving

Poach, bake or broil salmon steak. Flake salmon and combine with remaining ingredients. Shape into two patties and broil on a lightly oiled broiler pan for 3 minutes per side, or until golden. Serve on roll spread with dijon mustard and topped with red onion and tomato. POACHED BLUEFISH WITH HORSERADISH-DILL SAUCE (1 serving)

1/2 cup white wine

1/4 cup water

3 whole peppercorns or 1/2 teaspoon cracked black pepper

1 bay leaf

4- to 6-ounce bluefish fillet

FOR THE SAUCE:

2 tablespoons plain low-fat yogurt

1 tablespoon mayonnaise

1 teaspoon horseradish

1/2 teaspoon dried dill

Dash hot pepper sauce

Bring wine and water to a boil in a skillet. Add peppercorns or cracked black pepper, bay leaf and bluefish and lower heat to just below a simmer. Cover and cook for 6 to 8 minutes.

Mix all sauce ingredients together and serve over fish. This dish is excellent served cold, and the remaining sauce can be used as a sandwich spread or with cold chicken. MARTY'S MACKEREL (1 serving) 1/4 cup sliced mushrooms

1 scallion, chopped

1 clove garlic, minced

1/4 cup white wine

2 teaspoons dijon mustard

1 teaspoon soy sauce

4- to 6-ounce mackerel fillet

Heat a nonstick skillet until hot. Add mushrooms, scallion and garlic and cook until mushrooms are slightly wilted, about 1 minute. Mix wine, mustard and soy sauce together and pour into hot skillet. Add fish and cook about 4 minutes, turning fish once. Place on plate, pour over pan juices and serve. SARDINE SALAD SANDWICH (Makes 2 sandwiches)

3 3/4-ounce can sardines packed in soybean oil, undrained

2 teaspoons capers

1 tablespoon red wine vinegar

2 teaspoons lemon juice

Few drops hot pepper sauce

1/4 cup chopped red or green bell pepper

2 onion rolls

4 spinach leaves

1 plum tomato, sliced

Empty sardines into a bowl and break up with a fork. Add capers, vinegar, lemon juice, hot pepper sauce and bell pepper and stir to combine. Spread on one side of onion roll. Top with spinach and tomato, cover sandwich with remaining half and serve.