I think it is very unusual that Japanese endemic species salamanders are still kept in European zoos (although the Japanese Giant Salamander, also a species endemic to Japan, has disappeared from European zoos).
Indeed. I would have loved to learn more about how the zoo acquired all these species, if there's any breeding attemps or successes, or if there are plans to keep any of these on display at some point.
However, I had limited time during this backstage tour so my priority was actually seeing these species. Which wouldn't have been possible without the help of the staff member, who was willing to move some rocks and plants around to find some of the species that like to hide!
All I know is that the zoo keeps at least 2 individuals of this species, but we didn't visit every single tank so there might have been more.