The hadal snailfish, Pseudoliparis amblystomopsis is a species of snailfish

Snailfish

Snailfish are scorpaeniform marine fish of the family Liparidae. Widely distributed from the Arctic to Antarctic Oceans including the northern Pacific, the snailfish family contains 30 genera and 361 species. They are closely related to the sculpins of the family Cottidae and the lumpfish of the...

, described by Anatoly Petrovich Andriashev in 1955.

In October 2008, a team of researchers from the University of Aberdeen

University of Aberdeen

The University of Aberdeen, an ancient university founded in 1495, in Aberdeen, Scotland, is a British university. It is the third oldest university in Scotland, and the fifth oldest in the United Kingdom and wider English-speaking world...

's Oceanlab and the University of Tokyo

University of Tokyo

, abbreviated as , is a major research university located in Tokyo, Japan. The University has 10 faculties with a total of around 30,000 students, 2,100 of whom are foreign. Its five campuses are in Hongō, Komaba, Kashiwa, Shirokane and Nakano. It is considered to be the most prestigious university...

's Ocean Research Institute discovered a shoal

Swarm

Swarm behaviour, or swarming, is a collective behaviour exhibited by animals of similar size which aggregate together, perhaps milling about the same spot or perhaps moving en masse or migrating in some direction. As a term, swarming is applied particularly to insects, but can also be applied to...

 of P. amblystomopsis at a depth of 7700 metres (25,262.5 ft) in the Japan Trench

Japan Trench

__notoc__The Japan Trench is an oceanic trench, a part of the Pacific Ring of Fire, in the floor of the northern Pacific Ocean off northeast Japan. It extends from the Kuril Islands to the Bonin Islands and is at its deepest. It is an extension of the Kuril-Kamchatka Trench to the north and the...

. These are, to date, the deepest living fish ever recorded.