It's been a while since I wrote about eating fish raw, so I thought I'd give you a little update.
In the past, I thought that farm-raised salmon is safe to eat raw without freezing because the risk of parasites is almost non-existent. It turns out to not be completely true. The risk of parasites is relatively low in farm-raised salmon compared to wild salmon, but it's not non-existent. Farm-raised salmon is raised in the ocean in large cages. They are fed pellet food, which is parasite free, but there is nothing to prevent an occasional infected shrimp from sneaking into the cage and getting eaten by a salmon. So, what does this mean to all you sashimi and gravlax enthusiasts? It means that you might want to wrap your salmon tightly in plastic wrap, place it in a zip lock bag, and freeze for 7 days before using in uncooked preparations. This will kill any parasites. To defrost, place in the fridge for 24 hours before use. Luckily, farm-raised salmon is very fatty and can withstand freezing very well without suffering in texture (at least if you freeze for a very short period of time).
I would also like to bring another fish to your attention that I didn't write about in my first "Raw Fish" post -- arctic char. It looks like salmon only smaller, and tastes like salmon with a texture and flavor that are a tad more delicate. Since it's raised in land-based, closed-circle farming system, it's parasite free and can be eaten raw without freezing. Of course, it still needs to be very fresh to avoid bacteria risk, so you'll need to find a fishmonger that moves large volumes of char and is in control of when the fish gets filleted (the longer it's kept whole, the less bacteria will grow on the flesh). Char is absolutely luscious, low in mercury, environmentally-friendly, and retails for mere $11/Lb. That's a steal!
In the Boston area, I get my char from Captain Marden's. But I am sure there are other places that carry it. Make sure to ask how long ago it was filleted. If it's less than 2 days ago, I'd serve it raw, but more than 2 days, I would hesitate.
If you are not particularly squeamish and want to know more about parasites:
Cod Worm (FAQ about it)
Anisakis and Tapeworm