I got three Keyholes when they were young and I did not bother to sex them. Now there's two males and a female, all fully grown, except one male is larger (larger male = A, smaller male = B). A and the female paired up and B ended up cowering in the corner of the 65-gal behind a filter. Both A and female were agressive towards B, although in that gentle Keyhole Cichlid way. I moved B to another tank. When I did, the pair clearly "missed" him. I saw them looking behind the filter. Meanwhile, B looked miserable in his new tank. After about 2 weeks of separation, I put B back in. Amazingly, they no longer chase him to his corner, but have reached a kind of truce. While A and the female still gently shoos him away, B no longer cowers in the corner. It's amusing, too, because B still tries to horn in on A's girlfriend when A isn't looking.