Green terrors will get up to 12" long and actually have teeth. So if they get agressive they will do some damage if they have smaller fish in the tank. We had two 1/2" terrors in with adult cichlids, and a couple of fulu's about 3/4" and the terrors killed one of the fulu's tore it's tail all up and killed it, then took care of it's other fins before got home.
Green terrors now have their own tank because they were holding their own at 1/2" with adult african's. So I'd be cautious of putting them in with your tank. Just my experience.
p.s. when terror's get bigger they will eat feeder goldfish whole.
p.s. when terror's get bigger they will eat feeder goldfish whole.