It occurs to me I have never seen, eaten or even heard of sushi or sashimi made from freshwater fish. Why is this? I could only think of freshwater parasites as a possible reason( the dwarf tapeworm comes to mind).However, aren’t ocean fish just as susceptible to parisites? So what’s the straight dope?
I don’t really have the time to type something longer, sorry.
While it’s probably true that parasites may be an issue, there’s a simpler factor to consider:
Japanese freshwater fish are rather small and thus harder to prepare. You should also consider the fact that the Japanese varieties of freshwater fish don’t taste all that good raw.
That being said, here in Japan, you can find freshwater fish sushi, though it’s not that common.
Here is a picture of trout sushi. Often, the fish will be cooked before being made into sushi as in the case of this ayu sushi or the much more common eel sushi.
Here is a tiny picture of ayu sashimi.
Certainly you have heard of eel sushi.
As originally mentioned by jovan, most would consider this catadromous (living in freshwater, but migrating to and spawning in salt water) species a “freshwater” fish.
Anecdotal reply: Sushi/sashimi was invented/discovered by fishermen who were days out at sea and didn’t have anything to eat. So they just cut up and ate the raw fish that they caught. Freshwater fish would mean they’re on land, so no need to eat raw fish.
Actually, for sushi, that’s not true. Sushi was originally a conservation method. Slices of fish were sandwiched between layers of vinegared rice and left to ferment. In the Biwa lake area, they still make a similar preparation called funa-zushi. Here is a nice pictorial of how it’s made. It’s utterly vile - definitely an acquired taste that takes a few decades to acquire. It’s kind of like what I imagine lutefisk to be like.
It’s worth noting that the widespread consumption of raw fish is fairly recent. I used to live in an extremely remote fishing village - quite the time warp, really. It was almost impossible to buy fresh fish at the market as it was almost entirely dried or frozen. In an era where refregiration didn’t exist you tried to make things last longer by either cooking, drying or fermenting them. Eating anything raw was a great luxury.
Good point, here in the Great Lakes region we have many varieties of stocked salmon which, though originally ocean fish, live out their entire life cycle in freshwater. I wonder if any of our local joints use them.
I’m not familiar with the species of eel prepared and eaten raw, I suppose I just assumed it was a saltwater variety as well.
While there may be many types of eel sushi prepared and eaten raw, I have noticed that, at least on the East Coast, American Eel(Anguilla rostrata)is most common and usually served cooked.
As I understand it, our freshwater eel is also considered a delicacy in Japan. In fact, local conservation authorities may even report problems with export market (or local specialty market) demand for young eels.
Not all seafood used in sushi is raw.
Shrimp (ebi) may be either poached or raw for sushi. Octopus (tako) is usually boiled.
Some fish is marinated or pickled, such as mackerel (saba) or sardines (iwashi).
Both fresh-water (unagi) and marine eel (anago)sushi are always grilled. Also, pike conger (hamo, a summer delicacy, is always cooked.
The existence of parasites is the main reason river fish aren’t served raw.
Anyone who’s seen the waters of Lake Biwa would never want to eat funa (crucian carp) raw, cooked, or fermented!