If you like so called "White Tuna" at sushi places, be careful. Those really white and oily fatty fish was banned for consumption in Japan in 1969 because its high content of fat is indigestible to humans and having laxative effect. You can get really sick if you eat a lot. The white tune isn't really tuna either. Albacore tuna is a kind of tuna, but the white tuna I'm talking about is really a deep sea fish called escolar.
It's fatty and tasty, but can make you sick or run to a bathroom. Watch out.
I consider any sushi place serving this "White Tuna" to be unauthentic. We should eventually ban this fish in the U.S. too.