" I have had Vieja pin larger cichlids like dovii and managuense in the upper corners of a tank, shred and kill them. "
Thats ****ed up fish keeping!!
Nope, that's what can happen if you keep cichlids. Even if you provide a big enough tank etc.
It's actually a good example. It may work several times for a lot of people but you can always be unlucky and get the one individual fish with an outstanding character that suddenly "snaps". Means it just shows the more extreme end in the range of natural behaviour. In the evening everyone is doing good and in the morning you wake up and see dead fish.
Duanes is doing everything right by telling everyone about this kind of incidents to make people more aware.
It was said here that Astronotus is more aggressiv than Vieja. But that's just a point of view.
Yes, an Astronotus will show more aggression in the average compared to most Vieja but if a Vieja really wants it can make an Oscar look like a puppy. It simply has the more dangerous set of teeth and jaw structure.