"That being said, repts don't live in a vacuume in nature and there are successful mixed tank combinations."

I don't know why this argument keeps being repeated, any responsible would indicate that, being in an ecosystem, immediate contact with one another usually results in predation. The proximity with amphibians in the wild with that in captivity is of much difference.

There are successful mixed tank combinations. However, what apparently seems like a lack of aggression, may actually amount of an unapparent build up of stress. Your set-up may work. With regards to toxicity, definitely as soon as one media comes into contact with the other. I will quote caudata culture's study in saying, "When discussing the results of their findings they said, “All species of newts tested had toxic skin… . The symptoms were typical of tetrodotoxin…. The [adult N. viridescens] were less toxic than the efts… both C. pyrrhogaster and P. hongkongensis were about ten times as toxic as adult N. viridescens or about as toxic as the juvenile eft stage.”


Notophthalmus viridescens also ends up to be primarily aquatic, do note.