Advertisement So, in general one would keep a tarantula in a container roughly 3x its leg span in width depending on the species whether it is terrestrial and of course more height for an arboreal more substrate for a fossorial etc... But is there really a downfall to keeping a T in a roughly larger enclosure? other than giving it more space to roam. I understand you wouldn't necessarily know where your T was sometimes. However, wouldn't that save from the trouble of constantly needing to rehouse an Old World per say? I just wanted some opinions on this.