damn bro u can't keep anything with that monster fish man. sorry to tell u the bad news. It will kill any small fish or try to kill larger one. i have ne a while back and that the most aggresive fish i have.
All depends....408schmokin has a huge jardini w/ some gars and large bichirs...there is even a small wolf fish in there....as well as some rays. So it can be done.
i had my jar with 3 other aro's, a GG, a tropical gar and a fire eel and he was the one who got picked on so it's all fish dependant. my advice is to get them small and keep them with bigger tankmates from the start so they never are the aggressor. JMO