Not sure if this is applicable for Chowhounds, but the new fish store that opened up in Sparks can get sashimi-grade fish, and he can get all kinds of fish by request. Coast to Coast Seafood is at the intersection of McCarran and Prater. It's in the same area as the Bank of America, kind of tucked back into a corner, but it's worth the trip. If you want something but can't get there until later in the day, call and he'll hold it for you. This is good because they sometimes sell out of things.
Again, I know this is mostly restaurant commentary, but I thought the ability to get sashimi grade fish might be good news for some people.