Exactly thisGet multiple tanks and seperate the fish. Only certain arowana will mix, you'll just have to do alot of trial and error until you get ones that don't fight.
yup, mixing silvers is hard enough.. the asians seem to basically have the same temper as the aussies in some cases.. I would put dividers in that tank, get them used to other fish with the same type of swimming pattern and colour as the other arowanas and try until it works but never unattended until you are absolutely sure it will work..