What aquarium to choose for a reptile?

[androaqua]

My kid brought home a bearded dragon (don't ask how it happened) i'm desperate, help pls. How big should it be for him to feel comfy?

[GTX]

This site is focused on fish tanks. Most likely some members have reptiles too, so there is a slim chance for a better answer than this one.
https://www.google.fi/search?q=bearded+dragon+care