Is the Yokozuna Slickhead the World’s Largest Deep-Water Fish?

Scientists believe it to be an ultra-rare fish species.
Yokozuna slickheads on camera
Video of six slickheads was captured by Japanese researchers. Courtesy JAMSTEC

Japanese scientists have captured rare video footage of a large, nearly all-black deep-sea bony fish they believe is the largest fish found in the deep oceans of the world, according to Marine-Earth Science and Technology (JAMSTEC). It was first reported July 1 in Frontiers in Marine Science journal.
Scientists lured the oversize “slickhead” to a bait container on bottom 1.25 miles deep, 250 miles from Japan’s Suruga Bay, located southwest of Tokyo.

Three cameras were positioned around the bait container to record what fish would do. One of the cameras got video of a giant yokozuna slickhead driving away other fish from the food. They calculated the size of the oversize slickhead at just over 8 feet in length. The estimate was based on the location and size of the bait container to the fish.

Biologists believe the deep-water slickhead is an apex predator which lives in the darkest depths of the oceans.

Six yokozuna slickheads had previously been caught, with the largest only 4.5 feet long.

Researchers collected DNA samples from the deep-water study area confirming the presence of slickheads, which they believe is the world’s largest bony fish living in water deeper than 1.25 miles.

“The one spotted this time was so huge that we repeatedly recalculated its size,” said Yoshihiro Fujiwara, a researcher for JAMSTEC. “There is a possibility that large unidentified deep-sea fish variants inhabit other waters as well,” he said.