Smalltooth sawfish
Smalltooth sawfish are extremely vulnerable to overexploitation because of their propensity for entanglement in nets, their restricted habitat, and low rate of population growth. The species is listed as critically endangered by the IUCN Red List. Historically it was found in 47 countries, but it has been extirpated from 16 and possibly extirpated from another 25, leaving only 6 countries where it certainly still survives. In terms of area this means that it certainly survives in only 19% of its historical range. It is the only sawfish that certainly still survives in the United States (the largetooth sawfish, "P. pristis", has likely been extirpated from this country), and it has been listed by the National Marine Fisheries Service as endangered under the Endangered Species Act since 2003. It is estimated that the smalltooth sawfish population in the United States now equals less than 5% of the historical population in this country. In the United States it once occurred from Texas to New York (northern range as summer visitors), but today it is essentially limited to Florida. In the Everglades region of Florida the population is now stable and possibly slowly rising. Other countries where it certainly survives are the Bahamas, Cuba, Belize, Honduras and Sierra Leone, but whether it survives in the Western Gulf of Mexico or off the Atlantic coast of South America is unclear. The species is listed on Appendix I of the Convention on International Trade in Endangered Species.
Snailfish
In October 2008, a UK-Japan team discovered a shoal of "Pseudoliparis amblystomopsis" snailfish at a depth of approximately in the Japan Trench. These were, at the time, the deepest living fish ever recorded on film. The record was surpassed by a snailfish that was filmed at a depth of in December 2014 in the Mariana Trench, and extended in May 2017 when another was filmed at a depth of in the Mariana Trench. The species in these deepest records remain undescribed, but it has been referred to as the "ethereal snailfish". The deepest-living described species is "Pseudoliparis swirei", also of the Mariana Trench, which has been recorded to . In general, snailfish (notably genera "Notoliparis" and "Pseudoliparis") are the most common and dominant fish family in the hadal zone. There are indications that the larvae of at least some hadal snailfish species spend time in open water at relatively shallow depths, less than .