
The world’s deepest fish (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
Scientists have made new findings about the depth where fish can still survive.
A young Pseudoliparis-snailfish (the species has yet to be determined) was filmed on 15 August 2022 at a depth of 8,336 meters below the surface in the Izu-Ogasawara Trough near Japan. Guinness world records have Tuesday confirm it is the world’s deepest fish ever.
The unprecedented depth – more than twice the vertical height of Fuji, the highest mountain in Japan, is believed to be biologically the deepest level at which fish can survive.
A few days later, during the same expedition, there are two P. belyaevi-snail fish retrieved from a depth of 8,022 meters. It was a watershed moment, because it was the first time that fish were caught deeper than 8,000 metres.
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A young Pseudoliparis snailfish (species unknown) at a depth of 8,336m below the surface (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
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The snailfish investigates, but the bait has already been eaten off the camera stick (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
Marine biologists from the University of Western Australia (UWA) and Tokyo University of Marine Science and Technology (Tumsat) documented the snailfish during a two-month survey on the research vessel DSSV Pressure Drop (now renamed Dagon).

Vlnr Toshio Iseki (President of Tumsat), Kaoru Ishikawa of Guinness World Records, Alan Jamieson on screen, Hiroshi Kitazato (Tumsat) and Janine Pitt (of the Australian Embassy in Tokyo)
The expedition was supported by Caladan Oceanic and Inkfish and filmmakers from the Japanese broadcaster NHK were also on board.

Professor Alan Jamieson (Foto: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness-wêreldrekords)
The lead scientist was UWA Professor Alan Jamieson, founding director of the Minderoo-UWA Deep-Sea Research Centre.
Jamieson is a consultant for Guinness World Records on deep-sea marine life and is the world leader on hadeel organisms – in other words organisms that survive deeper than 6,000 metres. He made several record discoveries during his career.
This includes, among others, the diepste pylinkvis (6,212 m), die deepest octopus (6,957 m), the deepest decapod (7,703 m) and the dipste hidroso (10,063 m).
Jamieson says temperature and pressure have an unsettling effect on cells. Fish are therefore likely to be able to survive deeper under the sea in warmer water. “Two years ago we published a study on ultra-deep sea fish and determined that the deepest would probably be off Japan’s coast, as the trough here is deep enough and slightly warmer than the previous record in the Mariana Trench. And indeed, it was!”
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The deepest octopus spotted in the Java Trough (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
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The deepest decapod spotted in the Japan Trough (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
According to him, a depth of between 8,200 m and 8,400 m would be the deepest where fish could survive. “Fish use an osmolyte in their cells that balances pressure. This prevents the cells from exploding at depth.”
The previous record for snailfish was in the Mariana Trench in the western Pacific Ocean on May 18, 2017. The Japan Agency for Marine Earth Science and Technology (Jamstec) reported A snail fish was spotted at 8,178 m. The Mariana Trench, 320 km southwest of Guam, is home to the ocean’s deepest point – the 10,935 m Challenger Deep.

The previous record holder for deepest fish was the Mariana snailfish (P. wirei) spotted in the Mariana Trench (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)

As proof that the snail fish at 8,336 m was not a one-off event, numerous other examples were filmed at a depth between 7,500 m and 8,200 m in the Izu-Ogasawara Trough (Photo: Alan Jamieson/Minderoo-UWA Deep- Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)

Camera poles with bait are an effective way to film deep-sea marine life (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
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The research vessel Pressure Drop (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)
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The research vessel Pressure Drop (Photo: Alan Jamieson/Minderoo-UWA Deep-Sea Research Centre/Caladan Oceanic/Inkfish via Guinness World Records)