If you get them a comfy chair and a large HD screen with an infinite entertainment package and terabit internet you can get by with a smaller enclosure. Many humans provided these diversions become quite sedentary and won't move around much at all.
Cool thread. I pray for you that you didn't purchase my girlfriend. You'll be nagged to death in the first parsec if she gets hungry or your human tank doesn't come with WIFI.
Are you getting top view or side view humans? You know you need a minimum 2-loop filtration system? Do you know about cycling? Make sure to read the stickies in the setup & filtration section. BTW, F0 humans are almost impossible to get nowadays. To much crossbreeding. The variants don't even breed true anymore.