Would an umbee be an appropriate predator for culling small hericthys? I used to have a clown knife who did this well, but since his passing I need a replacement.
A big one will definitely eat them if they are small enough to fit in it's mouth (he will also go for them if they are slightly bigger to but expect a mess). I think a large catfish would be a better choice but if you don't have one any large cichlid can work. Just don't feed it a diet exclusively of culls.
Jags work great too, so would a dovii. I like my synodontis cats for this personally. Depends on how big the calls are. Gotta make sure to get em eating pellets too or you'll get the problems associated with a diet too high in protein