Which Catfish?

you might be in for a challenge to find not too aggressive new world cichlids. btu for a catfish i would suggest a synodontis. they are native to africa but do very well in most big cichlid tanks if raised with the cichlids, and would help keep it a little cleaner. not ever feeding the cichlids live food will also give the catfish better chances, among helping to keep everybody in the tank healthier.

Relatively peaceful New World cichlids:
Mesonauta insignis (festivum), Aequidens pulcher (blue acara), Aequidens portalegrensis (port acara), Heros severus (severum), Cryptoheros sajica, Cichlasoma urophthalmus (Mayan cichlid), dwarf pike cichlids. There are others but those are my favorites.

Ideal catfish companions would include any of the talking or "raphael" cats (available in spotted, striped, or plain), hoplo cats or pretty much any catfish species you like that will grow to 7 or 8 inches. Raphaels and some hoplos will top out smaller, but being well protected by armor and/or spines will discourage any cichlids from harassing them. There are also piles of pleco species that would be compatible, if you're so inclined.