Chris and I have wondered why sometimes a sushi dinner - and from a high-quality place mind you, because Chris can smell a not-so-fresh-fish from thirty paces - we both go running for the restroom. And I do mean running. It's never a mild thing, either: we're either fine, or the meal shoots through both of us.
The reason why: many sushi joints serve up a fish called Escolar in place of tuna. Escolar contains gempylotoxin, which "may lead to intestinal cramping and diarrhea".
It should be telling how bad for you this fish is by the way Japan treats it. The nation that eats every sea critter it can get its hands on, creepy, yucky, endangered, poisonous, or otherwise, has banned Escolar from consumption since 1977.
Equally baffling and repugnant, many restaurants also serve up endangered species.
It is unclear whether the restaurants knowingly serve up the wrong fish. I suspect in the case of the endangered fish, it is accidental, because a rare food could potentially be sold on the black market for a much higher price, while cheaper substitutes for tuna are easy to come by. I would give the restaurants the benefit of the doubt, but in this day and age, I call their mistakes negligence.