On Fla. Menus, a Favorite Fish Experiences Identity Theft

"It's scary, because people don't know what they're eating," Kinsey said.

Repeated revelations of fake grouper have scandalized restaurant-goers across Florida, and made them doubtful at the dining table.

In August, the St. Petersburg Times reported that at six of 11 area restaurants sampled, the "grouper" was actually something else, according to DNA tests. One restaurant was charging $23 for "champagne braised black grouper" but was instead serving tilapia.

A television station in Fort Myers and the Daytona Beach News-Journal followed with similar findings.

"People who don't know us are asking, 'Is that really grouper?' " said Stephanie Berry, a manager at Dockside Dave's St. Pete Beach, which many locals say serves the best grouper sandwich.

The texture and taste of real grouper are much different from those of the Asian catfish, which is its most common substitute. Grouper costs more because it tastes better. Moreover, Asian catfish filets are often thin and small; those of grouper, a much larger fish, are larger and thicker.

Exactly whom to blame for the fraudulent fish is a matter of debate. Some said anyone in the business should know the difference. Others said it is possible that the restaurants are being victimized as much as consumers are.

"If you order grouper and it says grouper on the box, what else can you do?" said Brian Connell, general manager of the Fourth Street Shrimp Store, a St. Petersburg restaurant. "A lot of honest people are catching a bad rap on this. We haven't been in business for 20 years by deceiving people."

According to the state tests, the restaurant was serving green weakfish as grouper.

The samples from that eatery and the others were tested by David Price at the Whitney Laboratory for Marine Bioscience in St. Augustine, part of the University of Florida.

Using essentially just a crumb of each alleged grouper, Price identified the type of mitochondrial DNA in each fish, then tried to match it up against one of about 100 grouper species in a genetic database maintained by the National Center for Biotechnology Information.

For 22 of the 24 fish samples, Price determined the species -- grouper or not -- by matching 99 percent of the sample DNA to grouper DNA. The remaining two were far enough away from any known grouper DNA that he could be sure that they were not the fish the restaurants had described.