Arowana swimming weird

[MariaS]

I did not put them all in first I put some small cichlids in first to see how they would do and they did fine for a 2weeks and then I bout the Aro, then the bicher and then the Arapaima like a week or two between each other.

It could be she hurt herself in which case there is not much you can do except water changes
and keep the water as clean as possible and hope she recovers

However, two weeks is nowhere near enough to cycle a tank even though your cichlids were fine
My first priority would still be to check the water parameters just to make sure and then take it from there

 

[Coryloach]

If the tank has been running for 5 months, its probably now cycled. The problem with cycling a tank with fish is that the effect of the initial bad water condition has a delayed effect and fish used in cycling don't last past the year mark...