The sushi menus listed "white tuna," but Minneapolis health inspectors determined the fish should have been labeled by its real name -- escolar. And if customers knew about the fish's reputation, they might stick with the California roll.

At least four Minneapolis sushi restaurants were found to be serving escolar and calling it something else in the second half of 2011, according to city Department of Regulatory Services inspection reports.

Escolar is edible and legal in the United States, but the U.S. Food and Drug Administration advises against any sale of the fish. It's packed with an indigestible waxy substance called gempylotoxin that can make people who eat too much of it ill for days with diarrhea, nausea, cramping and other effects.

Online discussions about escolar range from praise for its rich, buttery delicacy to condemnation as the "Ex-Lax'' of fish.

City inspectors cited four restaurants for mislabeling escolar: Tiger Sushi, Mt. Fuji Restaurant, Wondrous Azian Kitchen and Wasabi Fusion Restaurant. Another restaurant, Teppanyaki Grill & Supreme Buffet, failed to list escolar in its sushi bar consumer advisory even though it was served. Another restaurant was selling escolar under the name of "white fish" in 2010, but has stopped doing so.

The eateries used the names white tuna, super white tuna, bincyo and white fish instead of the only FDA-approved name, escolar. Inspectors discovered the illegal misnaming or omission by comparing invoices and in-stock product against menus, said Curt Fernandez, manager of the city's Department of Regulatory Services & Emergency Preparedness.

Wasabi's manager, Takeshi Hatori, said his menu included an item called white tuna, but he said that "the server [would] ask the customers, do you mean the escolar or the albacore tuna?" He said he's in the process of changing his menu.

All the other cited restaurants have corrected their printed menus, according to Fernandez.

Tiger Sushi's owner, Lisa Mann, said escolar is "known all over the country as super white tuna."

"But all of our menus now clearly show the various names it is known by," she said. "And we do that so that we can keep things clear for consumers."

But as of Friday, Tiger Sushi and one other cited restaurant, Mt. Fuji, hadn't corrected their online menus. Mann said she doesn't change her online menu as often as her printed menus due to the expense. "But I imagine I'll have to do that soon," she said.

Restaurants that don't correct violations in a reasonable amount of time face re-inspection fees or other disciplinary action, Fernandez said.

White tuna is an incorrect name for any fish, including tuna, according to FDA spokesman Doug Karas. But the restaurants may not necessarily be at fault for the misnaming, he added. It's possible that "somewhere along the distribution chain somebody has renamed it."

Though escolar is legal to sell, "We request that people who sell it, either manufacturers [or] processors inform people who buy it about the effects it can have on people who eat it," Karas said.

Calls by Whistleblower to Mt. Fuji and Wondrous Azian Kitchen weren't returned.

When asked about any illnesses associated with local consumption of escolar, Fernandez said "we do not have an outbreak associated with escolar in Minneapolis."

A nationwide trend

The mislabeling of fish is a widespread phenomenon. Florida cited 186 restaurants in 2010 for mislabeling fish, the Sun Sentinel newspaper in Fort Lauderdale reported that year. Most of 24 cases of tuna substitution involved escolar. A study by Nova Southeastern University in Florida in 2011 found that all of the 10 restaurants studied sold escolar as white tuna.

A study by Columbia University and the American Museum of Natural History in 2009 found that five of nine white tuna offerings in restaurants in Denver and New York City were really escolar. The report said that the sale of escolar is banned in Japan and Italy due to health concerns.

The FDA inspects imported fish at the border as well as fish at domestic seafood processing facilities, storage facilities and shippers, but leaves most of the retail mislabeling issues to local and state authorities.

A recent advancement in the detection of mislabeled fish is through DNA barcoding. Six FDA laboratories test fish for certain gene fragments at any stage in the distribution chain, including at the retail level, to verify that the product is properly named, and as a side benefit, properly priced.

Seafood importers found to be misrepresenting their fish are put on a list and must prove that their fish is what they claim it to be before it enters the country.