The sliver of raw fish sold as white tuna at Skipjack’s in Foxborough was actually escolar, an oily, cheaper species banned in Japan because it can make people sick. The Alaskan butterfish at celebrity chef Ming Tsai’s Blue Ginger in Wellesley was really sablefish, traditionally a staple at Jewish delicatessens, not upscale dining establishments.

At Chau Chow Seafood Restaurant in Dorchester, the $23 flounder fillet turned out to be a Vietnamese catfish known as swai - nutritionally inferior and often priced under $4 a pound.

Those were among the findings of a five-month Globe investigation into the mislabeling of fish. It showed that Massachusetts consumers routinely and unwittingly overpay for less desirable, sometimes undesirable, species - or buy seafood that is simply not what it is advertised to be. In many cases, the fish was caught thousands of miles away and frozen, not hauled in by local fishermen, as the menu claimed. It may be perfectly palatable - just not what the customer ordered. But sometimes mislabeled seafood can cause allergic reactions, violate dietary restrictions, or contain chemicals banned in the United States.

Read the complete article by Jenn Ableson and Beth Daley in The Boston Globe