Nice mayan.
For tankmates, you could mix other cichlids (midas, black belt, etc.) in a much larger tank, like a 55.
Mayans are not recommended to be kept alone, as they are sociable fish, but need room to safely be with others. Right now I guess you could add a pleco to grow with her, but not much else comes to mind. Giant danios are good dithers, but can't remain in a 10 gallon forever, in my opinion at least and based on your stock list the arowana would probably make a meal out of the danios.
One idea is a tinfoil barb though, it could grow up with your mayan, be active and have personality and grow large enough to not be eaten by your aro.
Those are all I can think of for now.