Pseudoliparis amblystomopsis, or the hadal snailfish, is a species of snailfish from the hadal zone of the Northwest Pacific Ocean, including the Kuril–Kamchatka and Japan Trenches. In October 2008, a team from British and Japanese institutes discovered a shoal of Pseudoliparis amblystomopsis at a depth of about 7700 m in the Japan Trench. These were, at the time, the deepest living fish ever recorded on film. The record was surpassed by a type of snailfish filmed at a depth of 8145 m in December 2014, and extended in May 2017 when another snailfish was filmed at a depth of 8178 m. This deepest-water so-called ethereal snailfish remains undescribed, but a close relative found only slightly shallower in the Mariana Trench was described as Pseudoliparis swirei in late 2017.