Many nutritional guides and diet books suggest eating more fish, but few tell how to buy or prepare it, a Utah State University food science professor says.

"It's simple for consumers to select a one-pound package of fresh ground beef. But we are not quite so familiar with fish," Von T. Mendenhall said.Although most fish sold in Utah is frozen fish that has been thawed, Mendenhall said, the product should still be felt for freshness.

"The texture should be firm as well as slightly slick and slimy but not sticky. A fresh fish," he said, "should also be bright red in the gill cavity."

Serving size for the average adult, Mendenhall said, is 3 ounces of cooked, boneless fish. When buying fish, a 3/4-pound whole fish will equal the required cooked portion size, he said.

Mendenhall advises reading labels carefully and warns against buying "engineered seafood" products sold in place of expensive crab or shrimp.

The products are colored, shaped and flavored to look like real crab and shrimp, he said but are actually made from cheaper types of fish.