I stand by my earlier statement that if you just want to keep them you can keep multiple species in the same tank. As a very brief example I currently have:
A 20 gal with A. cacatoides, A. sp. "red lobes Rio Xingu" & N. transvestitus.
A second 20 holds A. honsloi, A. panduro & P. taeniatus.
A 10 gal with A. atahualupa & A. borellii
A 10 gal with A. uaupesi & A. mcMasteri
and so on.
These are just holding or community tanks. My breeding set ups hold only a single species.
All tanks have very heavy plantings and many caves. However, the fish rarely use the caves. If you ever have a situation where the fish resort to hiding in caves to avoid agression you probably have a problem.
Also, notice that most of the combinations I list are fish from different groups. You will usually have less agression if they are from different groups and will also reduce the desire to spawn with a different species.