dats of the same size and species will most deff fight alittle at least. But with the amount of other fish u have in there, and the amount of hiding spots you say u have, you should have no prob getting a few more.
So if I can find a different type i.e. Siamese Tiger or New Guinea Tiger they have a better chance of not fighting?
I'm going to grow them to about 6 inches before they go into the 240gal. I figure the Arowana won't try to eat them and the polypterus won't be able to.