Nice. I got one two months back and about the same size. I had it on Hai Feng pellets, now mixing in Hikari. You should try small crickets, bloodworms, krill, shrimp too.
Oh so you should be good, I thought it was just the two of them, though they are still young, as they grow would be where the problems would arise I'd suspect around 10"
i know some successfully grow out small aro as a group so they get a lone well when they hit 10" plus..just keep them together and grow them up, they should get used to each other in the tank.