Arowana and peacock bass
When larger they can tolerate eachother if that is what your asking. try looking on youtube.com under "peacock bass feeding" their is a guy on there who has 6-7 peacock bass in with 2 silver arowanas. Both get along.
The poblem is that peacock bass arent classed under either aggressive or not. Why? Because peacock bass is a general name,as their are several varities of peacock bass, ea. has its own aggression levels, size, and coloration.
Most LFS peacock bass are more mild. I would have to suggest getting a larger silver arowana with a small peacock bass. The bass will be able to handle itself, and u run a lesser risk of the bass getting into it.
type in "peacock bass feeding on shrimp" onyoutube. Again this guy has a video of those fishes + 1 clown knife and a few plecos and they are fine.
Generally silver arowanas tend not to be aggressive and both should be fine.
The worest situation is clear, you can lose either fish, but that is what you must expect when trying to go this, but always look at the arowana, for any signs of damages, any signs of scale or fin damage and you know it wont work,and it cant be forced, so seperate.