Hoki (a.k.a Blue Grenadier, blue hake, New Zealand whiptail, whiptail or whiptail hake)
It's a fish off the coast of Australia and NZ. It came to mind last night because it's one of the fish they used in the filet-o-fish at one point...it actually
does have a slightly sweet taste and has almost no bones and has a really nice filet.
Due to constraints on fishing them though I think it's a composite now of some kind with another species of fish in Alaska that I'll add when I post again so as not to get snapped