I have found that at 4"-6", this is the point where just about with "any" cichlid, that the alpha wants to get rid of any competition, and any female except the receptive one, and if there isn't a receptive one, he kills them all.
It is one of the reasons, I usually buy 6 to 8 juvies and grow them together, and expect to have the male kill all, unless he and a female become a mated pair.
I have had this happen countless times, from Central American Vieja to African Fossorochromis.
And even after a pair forms, the likelihood of a male killing a female in high.
Or a dominant female killing males.
I had a dominant female Tomocichla tuba kill a number of males before she settled on one (that she also eventually killed, after a few spawnings.
This is why many successful cichlid breeders divide tanks.
It is the nature of the beast. In nature to get away, a female need only swim 20 feet away.
They don't have that luxury in the confines of almost any aquarium.
And in this kind of alpha situation, dithers are often ignored by the dominant male.
Target cichlids have sometimes worked for me, but sometimes they are also killed in the process. I had an alpha male argentea first kill all other cichlids in a tank, and then knock of all its brothers and sisters.
