Most of the greenies I’ve kept have grown to around 10 inches and lived with some of my toughest fish, Jags, Doviis all sorts of Amphs. I usually catch them to use as dithers if my tank needs them. They are plenty tough enough, definitely not afraid and usually out eat my centrals, but that’s probably because they were wild caught. Maybe they grow slower in a colder climate, but in a heated tank they should pack it on. I would say that they are about as aggressive as an average Central American Cichlid.
