That top tank is beautifull, I'm guessing it is apprx 400g 72"(L) x 36"(W) x 36"(H) It looks like the tank I just picked up and am selling only mine is 24"(W) making it only 280g.
Camaro I believe you are correct "halimeda" I used to have some of that until it got eaten up by my urchin before I traded him. I really like the look of it when grown out like that... very nice!
I wouldn't say the tank is "understocked" as I don't think you can understock a tank... giving more swimming room, territory and feeding grounds to fish is a "good" thing!
But I understand what you mean, as they could easily accomidate many others in a tank that size.
How long has the big one been running?