We May Never Find a Fish Deeper Than This

Scientists have filmed the deepest fish ever observed, an incredible 27,349 feet, or 8,336 meters, deep in the Izu-Ogasawara trench southeast of Japan. The young snailfish was spotted calmly swimming by sea robots exploring the depths last September. The deepest fish observed previously was a snailfish at 8,178 meters in the Mariana Trench, which lies to the south and is very slightly cooler than Izu-Ogasawara, per the Guardian. "If this record is broken, it would only be by minute increments, potentially by just a few meters," expedition leader and University of Western Australia marine biologist Alan Jamieson tells the BBC, noting fish aren't believed to survive deeper than 8,400 meters.

The young fish of the genus Pseudoliparis was likely so deep as to avoid predators lurking higher up in the water column, per CNN. "What is significant is that it shows how far a particular type of fish will descend in the ocean," Jamieson tells the outlet. Though most snailfish types inhabit shallow waters, some have adapted to the extreme pressures of deep water—particularly in trenches, where they can find many tasty crustaceans. "Their gelatinous bodies help them survive" more than "80 megapascals, or 800 times the pressure at the ocean surface," per the BBC. They also lack a swim bladder, which helps species move up and down in the water column, but can be a disadvantage in the very deep sea.

Researchers from the University of Western Australia and Tokyo University of Marine Science and Technology also managed the deepest catch, pulling up two snailfish (Pseudoliparis belyaevi) from a depth of 8,022 meters in the nearby Japan Trench. It was the first time fish had been collected from below 8,000 meters, per CNN. Researchers attracted fish by placing bait on the arm of an undersea robot. Among footage released Sunday is a clip showing many fish and crustaceans enjoying a snack between 7,500 and 8,200 meters. The lone snailfish was filmed even deeper in the Izu-Ogasawara trench, just above the seabed, where crustaceans were also observed. (More marine biology stories.)