I would recommend a glass tank with screen lid. This will help keep the humidity up, but still have good ventilation. The tanks that I specifically love are the Exo-Terras. These are also great for glass-sticking herps lol. If the frog is sticking to one door, you open the other without risking the frog getting loose. They're also easy to access the frogs and everything else inside. For a trio, the 18x18x24 is a good size.
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Owned by the following;
1 male minilop rabbit
1 male shetland sheepdog
1 male maine coon mix cat
1 female long-haired syrian hamster
1 male sunglow motley corn snake
2 male white's tree frogs
2 female Leptopelis vermiculatus
1 male Leptopelis aubryi
1 unknown Leptopelis aubryi
2 female crested geckos
1 male crested gecko
6 unknown silver dollar fish
2 male gold gouramis
1 unknown african brown knife fish
1 unknown south american bumblebee catfish
1 unknown lemon spotted plecostomas