In a world where you can buy knock-off designer clothing at flea markets and on city street corners, it shouldn’t surprise anyone that knock-off designer foods would soon arrive. Who doesn’t want to go high-class on a low-class budget? However, as is often the case when buying a fake Rolex, you may not get what you bargained for — literally. Let’s say you order grouper at your local restaurant. You pay the high price for grouper, but in fact, you may be eating something entirely different — something far cheaper.

That’s exactly what “fish detective” Mahmood Shivji found when he went coast to coast ordering high-end fish at 150 restaurants. When he stopped in Kansas City, he found that 14 out of 15 restaurants — nearly all — had substituted cheaper fish such as imported catfish or tilapia for the red snapper on the menu, without telling patrons the truth. He went on to New York, Los Angeles, Charlotte (NC), and Florida, where he discovered that more than 50 percent of the restaurants tested had switched-out various fish items on their menus. He’s not a fish connoisseur with a refined palate; rather, he’s a genetics professor and he used fail-proof DNA testing.

Shivji isn’t the only investigator to uncover this story. NBC News in Kansas City followed up with its own investigation of 20 local restaurants, and they found an 85 percent deception rate. But some of the exposed restaurants cried “Innocent,” claiming that their supplier had deceived them. And in fact, the investigation did find supplier deception, too.

Given that grouper costs restaurants an average of $11 to $12 per pound, versus only $2.50 a pound for catfish, and given that the typical restaurant patron has no clue, it’s a huge temptation that many eating establishments, apparently, can’t resist. Most people don’t routinely eat high-end fish or seafood products at home, so they just don’t recognize subtle differences in taste, particularly when the fish comes swimming in Beurre Blanc or pesto.

Other than the rip-off factor, it might not be a big deal, except that you could be getting fish that isn’t particularly clean, healthy, or ecologically proper. Some species have been practically fished out of the water and shouldn’t be served, some may come from polluted waters, or be farm raised under atrocious conditions, and some may produce allergies. If you order a particular fish because you know it to be one of the healthier, safer varieties but end up eating a less healthy substitute, you have good reason to be outraged.

In fact, “seafood fraud” isn’t new — it’s just newly big news. For nine years between 1988 and 1997, the National Seafood Inspection Laboratory conducted an inspection and found that 37% of fish and 13% of shellfish, including products sold at stores, were mislabeled. The deceptions included false labeling, misrepresenting the true weight of the fish, adding water to bulk up the weight, and adding color or treating with carbon monoxide to make old fish look fresh (a technique also favored by the meat packing industry). The common substitutions found included replacing Pacific salmon with Atlantic salmon, sea bass with halibut, real crab with imitation crab, and flounder with Dover Sole.

Surprisingly, one of the few restaurants to emerge clean from the investigations was McDonald’s, of all places. McDonald’s actually tells the truth about its Filet O’ Fish, which turns out to be genuine Alaskan Pollock — a cheap, moderate-mercury fish in plentiful supply. Grouper, by the way, has a very high mercury content, plus it’s one of the threatened species on the “Eco Worst” list. If your restaurant pulls a slight of hand and substitutes tilapia, they may actually be doing you a favor. The Monterey Bay Aquarium’s consumer guide to ocean-friendly fish gives U.S. farmed tilapia its “best” rating and Central American farmed tilapia a “good” rating.

On the other hand, it advises consumers to “avoid” tilapia imported from China and Taiwan, where it says “pollution and weak management are common.” Unlike farm-raised salmon that are fed fish meal and have been shown to contain polychlorinated biphenyls (PCBs), contaminants and antibiotics, farm raised tilapia are plant eaters that grow well in high densities and resist contamination — at least in comparison to other farm raised fish. The bottom line is that you’re probably better off if your restaurant pulls a fast one and tricks you into eating tilapia (depending on where it comes from) instead of grouper, though your wallet may suffer the insult.

:hc