Apistogramma cacatuoides, aka. cockatoo cichlids, are a great fish for medium size tanks, around 10 or 20 gallons. The problem comes when you have more than one. At this point you have to manage their behavior. If you have a group that was raised together, and the tank is big enough, it isn’t usually a problem but when you introduce two strangers for the first time it can be difficult… not impossible but difficult.
For a long time I wanted to raise some but the opportunity never came until the local pet shop had a group of small ones for sale. They were too small to sex so and they had been in the store for a while without any buyers so I bought the group of 10 for $10. I put them in a 20 gallon tank with some oak leaves. All 10 grew up fine but they were all males.
As they grew up, they didn’t fight a lot, just enough to establish territories but not enough to have torn fins. I looked around for a female but none were to be had. I auctioned off all but 3 males at the Boston auction. Later, two of died from an infection of worms that infected all the fish. (More on this latter).
I got a female from a friend and introduced her to the remaining male. She killed the remaining male within the week. Later the same friend bought a male for me and while the two fish aren’t killing each other, they are ignoring each other. When it comes to cichlids , there are no rules as far as I can see. It’s a good thing I don’t run a dating site!
If you are interested in raising these or other South American dwarf cichlids, you should start with this site. http://dwarfcichlid.com/Apistogramma_cacatuoides.php
I am looking around for a good pair to try again. They really are an interesting fish and the males are about as colorful as fresh water fish get….with the exception of the annual killifish.
I wish I had taken some pictures of them but maybe I will this time.