The trouble with buttikoferi is getting them "not" to kill each other.
Best way to get a compatible pair is get as many as you can, the allow the alpha male will kill all other subordinate males, and then kill any unreceptive females, hoping there's one left that works.
Best to use a tank or swimming pool of 300 gallons or more with lots of places for females to hide from a rutting male. The bigger the enclosure better. I started out getting around 10 juvies.
My last ones hit almost 20 " and seemed ready to spawn, but the last female ended up dead after about 3 years.