Jarno,
This vivarium inhabits 11 adults, 6 females and 5 males. Right now i'm building them a new tank, 200x60x35, no sliding front-screens and fully
uncovered, lighting hanging above it and with a biological filtration-system.
A larger tank makes it easier to create several
environments within one tank, a swampy part, deeper water, a shallow water-part, slow current part, more "land", more basking-spots.
Although feeding and basking are very gregarious activities, Bombina maxima do like quiet and lonely hide-outs and it's easier to provide those in a larger set-up.
Han.