OP - you posted your question in the CA/SA section and you rec'd bad info referencing "harem breeding". You'll see that more with Old World species.
If you are looking to establish a pair of CA breeders, the best way is to be patient, acquire 6-7 juveniles of a species and raise them up together. You will notice a pair (or sometimes pairs) develop. Usually simultaneously, you will see the other fish experiencing violence from the pair(s), running for cover. Then is a good time to rescue the other fish but at the same time, add another dither species, something that is expendable. Hopefully the pair continues to bond and start breeding. Most CA's spawn monthly to every six weeks once a pair is established. You need to be careful after each spawn, particularly if you pull fry, that the male does not "blame" the female for the loss of fry and take it out on her. That, and just general aggression by the male in between spawning, sometimes leads to the need for dividing the pair during these periods, or setting up an incomplete divider, whereby the female can pass into a secure, divided area of the take without the male harrassing her.
As a fishkeeper, you need to think about why you want a breeding pair in the first place. Do you want to raise and sell the fry? Then you want to choose a species accordingly, one that is salable, but also one that is an easy-to-moderate challenge in breeding. Anything to difficult to breed could lead you to get discouraged, assuming your original goal continues to establish a breeding pair of fish.
Or do you want to generate fry as feeders? Then convict species work the best, and depending on the tank size, you can set up multiple pairs within a same arrangement and pull fry as needed - again, not a "harem" in the technical sense, but multiple, individual breeding pairs. if you want a true "harem" situation, post your question on Old World boards. Hope this helps-and good luck.