What's a Walu?

Last night, I met a friend for sushi at Kaz Sushi Bistro, located in downtown Washington, D.C. It's one of my favorite dining spots.

Among the different sushi I ate was a Kaz menu special called "Walu Toro." It was excellent. I wasn't sure exactly what kind of fish this was. Once I got home, I searched the web, found this food blog and realized that Walu is also known as Hawaiian Butterfish.

That made sense to me because the Walu sushi I ate practically melted in my mouth -- very delicate and tasty, not as dense as tuna. Walu is supposed to be wonderful when it's grilled (pictured above).