Thanks for the information -- very interesting.
Is it your understanding that salt-water fish are less susceptible to infection from bacteria?
In any case, I'd never eat raw fish from my local supermarkets. I'm reluctant to eat most of the dried out, nasty looking stuff they sell even when it's cooked! They do get some decent salmon, which is a big seller, and occasionally decent tuna and halibut, but I eye it (and nose it) very carefully before buying. I miss having a good fish market nearby!