That tempting seafood delight glistening on the ice at the market, or sizzling at the restaurant table in its aromatic jacket of garlic and ginger? It may not be at all what you think, or indeed even close, according to a big new study of fish bought and genetically tested in 12 parts of the country — in restaurants, markets and sushi bars — by a nonprofit ocean protection group, Oceana. In the 120 samples labeled red snapper and bought for testing nationwide, for example, 28 different species of fish were found, including 17 that were not even in the snapper family, according to the study, which was released Thursday. The study also contained surprises about where consumers were most likely to be misled — sushi bars topped the list in every city studied — while grocery stores were most likely to be selling fish honestly. Restaurants ranked in the middle.