What sort of cichlids - 1 inch apistos, 2 feet long Cichla or Boulengerochromis? This might seem like a harsh reply, but one mans cichlid is likely different to anothers. David Soares kept between 150 and 175 Apisto Cacatuoids in a colony in a 55, but equally, assuming it's 4 feet long you could keep a single oscar or other large, medium aggressive fish. Or you could keep a number say 4 or 6 , of medium sized cichlids like firemouths , spilurum.
Or you could keep a flock of peacocks , like 2 males 8 females, a flock of tropheus , say 12, or a whole load of mbuna.
There are lots of answers to this questions I'm afraid.