The issue of Oscars kept in a 55 gallon as well as bettas kept in a bowl is that in either situation, there is absolutely no way you could possibly mantain good water quality, which isn't the case with a silver arowana in a 6x2 tank. And stating that the reason aros jump is because they have nowhere else to go makes you a hypocrite and basically means that the vast majority arowana owners (and keepers of any other large fish in general, for that matter) are bad fishkeepers, because if you put a fish in a glass box then where the hell do you expect it to go? It isn't like your tank provides so much space that your aros can move in any direction and never hit a glass wall either. Going by that logic, keeping an arowana in any less than a 12,000 gallon tank is animal cruelty. If we all kept fish in "ideal" setups, then this website would no even exist, because most people wouldn't be able to afford to "properly" house anything over 6".