2 cichlids in a tank is a bad number, the subdominant one generally gets bullied too much, I have found. 3-4+ allows the aggression to be distributed a bit so that the little guy isn't getting 100% of the bully's attention. I would add a couple more appropriately sized cichlids.I also have a polleni cichlid(5inch) in the tank with him, who sometimes chase after him. Could it possibly be stress?

