Other problem is what else do I put in it as the tank yould seem kinda empty in 720 gallons of water.
That is a problem for you?!?! I'd kill to have half the fish available that you can get in the US. I'm keeping my black aro with a group of Geophagus altifrons, angelfish and a bunch of plecs. Your options are nearly limitless so long as it gets large enough not to be eaten and isn't aggressive towards the aro. My personal preference would be towards South American cichlids, Geophagus, Satanoperca, Uaru, Hoplarchus, severum, discus, etc etc, but there are plenty of other choices. Datnoids, large barbs/sharks, catfish, rays, bichirs, clown loaches are all potential tankmates.


