Safe choice. My black was always swimming around all of the water column so the aro being a top dweller wouldn't help if yours was like mine. But mine wasn't to bad aggression wise, he chose who he let live with him pretty much even acted as a protector to the bichirs it seemed. I have only kept mala with a silver for a few months back in high school. Never let any impulse allow me to be irresponsible and get another. The wolf was around a foot, the aro grew from 7" to 15-16". Only issue I had in the comm was a water cow goby tried eating the aro when it was smaller so I removed the goby for a month or so allowing the aro to grow large enough to not be eaten.