Mine is definitely aggressive, you should see it feeding, most of the times it bits the feeding paper during feeding.thanks but they are kind of pricey. have kept 2 before they are indeed nice fish how about your arowana is he aggressive?
He ate one of my algae eaters plaeco too.
Many a times seen chasing the leopard loaches, but they are fine.
I think what ever can fit the mouth of the arowana, can not be kept with it.
And the tank mates should be fast enough to swim away when chased by the arowana.