Noddy wrote:
We just have to wait for Marcus to chime in.
He has a less fortunate story about arowana and Oscar.
I had one for some time, but it didn't live long...
Dunno why exactly.
I have a RTG arowana, had it a little longer than Paul so still getting to know it really. It didn't workout with my oscar in fact it done so much damage to the oscars jaw it died. I was not happy

arowana don't show mouths like oscars they just snap out and bite. from all the arowana sites i have looked at 150g is minimum size tank needed. I still think it would be better suited in a shallow pond much larger. they feed fairly cleanly, not much waste ends up on the bottom, are very picky at what the eat, (mine will eat good quality king prawns but turns it nose up at smaller cheaper prawns) a lot of arowana won't eat pellets so you need to think more about diet. it is a true predator and will Savage like oscar. it wants to hunt. It likes a lot of water movement and don't like changing water conditions. you need to keep your parameters stable, including nitrates. its not good to have it rise then fall at water changes. be prepared to do a little more testing and changing. also need a bit of space at the top of the tank as they jump and feed on the surface. feeding can be very aggressive so the can hit the tank lid if you are not careful. this can damage the powerful but still delicate jaw or head. its a very majestic and wonderful fish to keep, and I am very happy to own it but it dose have more problems.
Just thought I'd add mine is doing well with clown loach, they can easy maneuver out the way of a snap and as they too are fast moving fish all seam to get on well.