I have found that in recent years, mixing species in large vivs or (especially) paludariums has become increasingly common and much more accepted than it was when I first began keeping frogs. I keep baja tree frogs with spring peepers but that's as much as I've done; I've seen many keep aquatic species with terrestrial/arboreal ones as well as combinations of frogs and toads or newts. What are the criteria for species that can be kept together? I keep my pseudacris frogs together because they are very similar, but many of the combinations i'm seeing are far less so. I'd love to keep a multi-species setup providing that it's safe- perhaps ADFs in an aquatic section with the aforementioned small tree frogs.