I had me a Vittatus, i grew it to around a foot. was a lovely fish but i lost my job at the time and had to sell up. bad times.
Definatley sounds like you need some sort of Pred to sort out the Cichlid overbreeding. got things going through my head to come up with an answer but its seeming difficult!
Clown Knife fish?? (Can not think of latin name at this specific time)
Tiger Shovelnose?? (Pseudoplatystoma Fasciatum)
Gar Fish?? of some sort. I don't know a lot about Gar's if i'm honest. although i wouldn't mind trying one of the shorter nosed variety, Alligator?
a Snakehead might do the trick, but obvious regulations in your area may apply. (Channa Micropeltes to be specific)
Would a Clarius be of any use??
Unless you starve some of the bigger fish like the Cats and Arowanas then they may turn to the cichlids as food??