Sawfish
The pregnancy lasts several months. There are 1–23 young in each sawfish litter, which are long at birth. In the embryos the rostrum is flexible and it only hardens shortly before birth. To protect the mother the saws of the young have a soft cover, which falls off shortly after birth. The pupping grounds are in coastal and estuarine waters. In most species the young generally stay there for the first part of their lives, occasionally moving upriver when there is an increase in salinity. The exception is the largetooth sawfish where the young move upriver into freshwater where they stay for 3–5 years, sometimes as much as from the sea. In at least the smalltooth sawfish the young show a degree of site fidelity, generally staying in the same fairly small area in the first part of their lives. In the green and dwarf sawfish there are indications that both sexes remain in the same overall region throughout their lives with little mixing between the subpopulations. In the largetooth sawfish the males appear to move more freely between the subpopulations, while mothers return to the region where they were born to give birth to their own young.
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 .