You could, but not for long once they reach 5 to 6 inches they get fiesty. I am not sure what yours looks like, but you probably don't want his fins nipped. He will out grow the 30 gallon in no time. It' not a good idea to put cichlids together in a small tanks. They tend to fight more because of the space issue. I would reccomend at least a 55 gallon. to get back to the original question you could probably put convicts of the same size in there. Be prepared to move them out once they get a little bigger.