i'd advise putting other community fish in first before the asian arowana whether it be RTG, gold or red because once they settle into the tank it will be harder to introduce tankmates as they will be quite aggressive. I found it better the other way around to introduce arowana later on for a community build out. just my 2 cents.
Funny you should mention that i saw a group of them today and was thinking about it..their lovelyI have a small school of striped silver dollars (metynnis fasciatus) in with mine and couldn't be happier. Their shoaling characteristics are very entertaining. They're fast and not really a snack for the Aro either.