In the Mississippi delta, they're farming a new kind of catfish

There's a new kind of catfish in the Deep South that's a far cry from the bewhiskered river bottom feeders caught by barefoot boys with cane poles and bent pins.

The delta area of Mississippi is now farming this traditionally strong-flavored fish with scientific methods of aquaculture.

The fishy taste has been lost, and the new breed of catfish lends itself to as many methods of preparation as chicken.

Here in this land of flowering magnolia, mimosa trees, and hospitable people, catfish has always been a staple. To help satisfy the demand, Mississippi produced 73 million pounds of dressed fish last year.

Cotton, soybeans, and rice are the traditional main crops here in the delta, with catfish now ranking fourth, although the industry is only about 15 years old. Some 70,000 acres are given over to the cultivation of the fish, which take a year and a half to grow from roe to table size.

Mississippians love their catfish, and dotted along the roadside are numerous restaurants advertising ''fried catfish and hush puppies.''

In the spring there's a catfish festival in Belzoni, and throughout the year a local restaurant, the Antique Barn, serves catfish in many guises - as a dip with crackers, as a pate, or stuffed with shrimp and covered with melted cheese.

North of Jackson, the capital city, is a restaurant called Fowler's Lodge, on the Ross Barnett Reservoir. Here Chef Tom Slough, who has prepared catfish for President Reagan, makes catfish the traditional way - deep-fried. His special hush puppies include catfish as well as plenty of onions.

Mr. Slough is also the party behind the National Catfish Cooking Contest, held recently for its 10th consecutive year.

The catfish farming process begins at Fishland Hatchery in Inverness, where the tiny eggs are kept in tanks of swirling water. After 18 days the fish are fingerling size and are transplanted to the outdoor ponds.

Each rectangular pond is about 20 acres in size, is fed by fresh well water, and holds approximately 80,000 fish.

Twice a day farm trucks drive back and forth on the levees that separate the ponds and spray pellets of food onto the water. The food, made locally in the town of Belzoni, is primarily corn and soybean meal with added fish meal.

As with many farms, there are problems with the elements. During the winter, the ponds, which are only four feet deep, can freeze and the ice must be broken.

In addition to the whole fish requested by some markets, farm-raised catfish come packaged in a variety of ways: pan dressed, in filets, and in steaks. Some are frozen and some sent to market on ice.

This year's winner of the National Catfish Cooking Contest, Kerry Terry of Meridian, presented a stunning mousse shaped like a catfish, with the green part of scallions for whiskers.

The second-place contestant, Minnesotan Mary Finnegan, prepared a catfish and fruit salad garnished with fresh strawberries.

Third-place Mark Beridon used a hot-pepper sauce marinade and served the fish with a mustard sauce. The runners-up made catfish relleno with green chilies and a catfish and corn frittata. Catfish Party Mousse 2 pounds catfish fillets or nuggets, fresh or frozen 2 quarts water 1/4 cup liquid crab and shrimp boil, or 4 cubes fish-flavored bouillon and seasoning 2 tablespoons salt 2 envelopes unflavored gelatin 1/2 cup cold water 1 package (8 ounces) cream cheese, softened 1 carton (8 ounces) soured cream 1 can (10 3/4 ounces) condensed cream of mushroom soup 2 hard-cooked eggs, chopped 1 cup finely chopped onion 1/2 cup finely chopped celery 1/2 cup finely chopped green pepper 1/2 cup chopped pimiento 1 tablespoon lemon juice 1 teaspoon Worcestershire sauce 1/2 teaspoon salt 1/8 teaspoon white pepper Salad greens Assorted crackers

Thaw fish if frozen. Bring water, crab boil or bouillon cubes, and 2 tablespoons salt to a boil.

Add fish, return to a boil, reduce heat, and cook fish for 8 to 10 minutes until fish is done.

Drain water from fish. Flake fish into small pieces.

Combine gelatin with 1/2 cup cold water and let stand 5 minutes. Dissolve over hot water.

In a mixing bowl combine cream cheese, sour cream, and soup. Blend until smooth. Add dissolved gelatin.

Add fish flakes, eggs, onion, celery, green pepper, pimiento, lemon juice, Worcestershire sauce, salt, and pepper. Mix well.

Pour mixture into a 1 1/2 quart mold or two small molds. Refrigerate until set (4 to 6 hours). Unmold onto salad greens. Serve with crackers or as a first course. Deep-Fried Catfish 6 pan-dressed catfish (1 pound each), fresh or frozen 1 cup buttermilk 2 tablespoons salt 1 tablespoon black pepper 1 1/2 cups cornmeal 1/2 cup flour 1 1/2 to 2 quarts peanut oil for deep frying

Thaw catfish if frozen. Score the fat part of each fish. Place in a deep container. Add buttermilk, salt, and pepper and stir to coat fish evenly. Refrigerate 4 to 6 hours or overnight.

Mix cornmeal and flour. Drain catfish and roll fish in cornmeal-flour mixture.

Deep fry at 370 degrees F. until golden brown. Drain on paper towel. Keep warm in oven until ready to serve. Serves 6. Sheila's Hush Puppies (From ''Festival Cookbook,'' published by Humphrey's Academy Patrons, Belzoni, Miss., 1983) 1 1/2 cups cornmeal 1 cup flour 1 teaspoon salt 1/4 teaspoon pepper 2 teaspoons baking powder 1 1/4 cups milk 2 eggs, beaten 1 onion, chopped 2 tablespoons melted shortening

Mix dry ingredients thoroughly. Gradually add milk, blending well. Add beaten eggs and chopped onion. Drop from a teaspoon into hot, deep fat and fry until golden brown.