The largehead hairtail, Trichiurus lepturus, is a very unusual fish which shipped off the factory line with a different set of operating instructions than the norm. Apparently, no one bothered to tell this species how fish are supposed to swim and orient themselves, so these guys swim by using their long, full-body dorsal fin which is undulated in a graceful, mesmerizing way.
Furthermore, the fish swim in an upright position and have a large head relative to their long tapering body which gives them a truly unique fish. This fact was not lost on the directors of the Kaikyokan Aquarium where they have built a large display especially for showing the wonder of the largehead hairtail.
Not only is this display bordering on the hypnotic, apparently the largehead hairtail is also pretty good eating and easy to debone.