You can try many other fish with arowana. The thing is in smallish tanks, it is often a gamble, especially with the more aggressive arowana as Asian and Australian. You can most certainly try with almost any tank mate that won't fit in arowana's mouth but watch closely and be prepared to remove the tank mates at any point.
Galantzspeed and I have not steered you away from trying an arowana, for two.
Thanks dear. My tank is a 150L × 50W × 80H in cm. If I buy suppose a silver arowana (extremely easy to get) which is living in a community tank. Maybe that's a good choice? The fish which is already used to other fish? I have seen in stores they have arowanas housed with big parrots or oscars or kois. In that case suppose I by a not very big arowana how much time I can have till it start to grow into a beast?