This is a picture of the Cichlasoma hedriki being approached by my Astatotilapia Latifasciata (Wolverine is what we call him because of his coloration and attitude). I originally had Wolvie in the 30 gallon but he got a bit too psycho for his tank mates. I switched him to the 90 and he's been doing great. I've actually even seen him bite the larger Dempsy . . .although he then runs like hell.
Here we see him making aggressive moves towards the Dempsy . . . my favorite is that look from the Dempsy of "You've got to be kidding, right?"