Comm Aro and Endi

Hello Sifus and forum friends

Appreciate advice as I have a 2.5 feet red Aro and I would like to comm with an Endi which is also about 2 feet in length.
I had once trying to comm my Aro with other tankmates i.e. mostly barbs, silver dollars and all kena whack till death.
I don't understand my Aro behavior or maybe his been kept alone for 3 years which results to his territorial behaviour.

I'm just into Endi and would like to see both fella live in peace & harmony
Any suggestions which I can tryout to successfully comm this 2 fellas?

Many thanks!