So here is the setup I use for metamorphosing fire salamanders. The first time I raised fire salamander larvae was in 2001 and I lost the first to drowning. Since then I've been careful to check large larvae every day and transfer them to a setup like this when their gills have greatly diminished (but not disappeared).
The setup consists of a food container, purchased in bulk from Costco, with dechlorinated tap water that just covers the salamanders, and then a large gravel area they can haul out on. The black colour of the container adds security. Once they have spent at least 24 hours on the gravel I transfer them to a moist paper towel setup and after a few more days they go in their grow-out setup.
The lid (not pictured) has 2-3 holes punched in it, which provides minimal ventilation so that the humidity level remains high while their skin is still changing into the tougher adult type.
The setup consists of a food container, purchased in bulk from Costco, with dechlorinated tap water that just covers the salamanders, and then a large gravel area they can haul out on. The black colour of the container adds security. Once they have spent at least 24 hours on the gravel I transfer them to a moist paper towel setup and after a few more days they go in their grow-out setup.
The lid (not pictured) has 2-3 holes punched in it, which provides minimal ventilation so that the humidity level remains high while their skin is still changing into the tougher adult type.