I've bred both ribbed newts (
Pleurodeles waltl) and blue tail firebellies (
Cynops cyanurus) so i can help with those.
Ribbed newts are really easy, so if yours aren't breeding its probably because you either have two males, have immature animals, or just haven't triggered them enough yet. What always worked for me (and many others) was to do a big water change and give them a big feeding. When you are doing the water change, be sure to add COLD water back in. And for food, something that gives off smell will really get them riled up. Chopped worms and bloodworms seem to do the trick.
For blue tail firebellies, a winter cooling period is necessary. I cooled mine at temps between 45 and 55F for around 2 months. During that period, the males developed blue on their tails and more spotting on their backs and sides. Now is a perfect time for you to start cooling. If you have them in a basement or garage, let it get cold. These guys will remain active and feed at temps of 45F or higher in my experience.
After a few months of cooling, gradually warm the tank back up to about 60 degrees or so.
Also, make sure to constantly check for eggs. This species will eat any eggs they find, and so if you don't remove eggs from the tank there is a good chance they'll get eaten.
As for the other species, they are pretty similar to the firebellies. A cooling period is necessary for many Caudate species to breed.
Here are caresheets for Marbled and Crested newts, there's a section in both giving info on how to breed them.
Marbled:
https://www.caudata.org/cc/species/Triturus/T_marmoratus.shtml
Crested:
https://www.caudata.org/cc/species/Triturus/Triturus_sp.shtml
Hope this helps :happy:
-Seth
