Spanish ribbed newts (Pleurodeles waltl) are another highly aquatic newt. Like Pachytriton sp., they are pretty big as newts go (6" individuals are not uncommon, and they sometimes get considerably bigger) and need some room. I suggest 2 or 3 for your tank.
Keeping fish with newts is tricky. If you must have fish, try inoffensive (and inexpensive) coldwater species such as white clouds or rosy reds. Be prepared to lose some fish. Avoid any fish that might nip fins (such as gouramis) and any fish with spines (such as otos and cories).
Ghost shrimp, cherry shrimp, and scuds are good tankmates/snacks; if you have some densely planted areas the shrimp should be able to breed in the tank.
Regular eastern (red-spotted) newts are aquatic once past the eft stage. Not as big as the paddles and ribbeds though, I don't think I've seen one over 4" ever.
