Well I found this information on a site, maybe it will help you:

I have found that an all-glass aquarium is quite appropriate as this species does not especially object to the 'openness' of glass. A 36-inch aquarium will quite comfortably house up to four specimens with a 3:1 or 2:2 male to female ratio being preferred where breeding is to be attempted. This must have a secure lid as, like most caudates, mandarin salamanders can escape out of the smallest gaps. Adequate ventilation is also essential.
http://www.amphibian.co.uk/mandarin.html