Do you know what kind of fish you're eating? Let's be very honest about the average American's palate: the average American is unable to distinguish a banana from a deep-fried Oreo cookie in a blind taste test. It is perhaps too much to expect the average American to be able to distinguish between perch and flounder. Which is probably why a lot of restaurants just sell any old fish and label it on the menu as "World's BEST Kind of Fish."
The NYT reports on a new study of NYC fish-selling establishments that found that "39 percent of nearly 150 samples of fresh seafood collected from 81 establishments in the city this summer were mislabeled." The especially fun part is that many of the mislabeled fish are actually fish that could be dangerous for you to eat: "Ninety-four percent of fish sold as white tuna was not tuna at all but in many cases a fish known as snake mackerel, or escolar, which contains a toxin that can cause severe diarrhea if more than a few ounces of meat are ingested."
Just accept that you have no fucking idea what kind of fish you're eating, and, furthermore, that mercury levels in your system are probably past all safe levels already. Or, just become a vegetarian. No one has trouble identifying a motherfucking carrot. (Except for the average American.)