Very cool, thanks for sharing.
A couple of times I have seen groups (at good fish stores) among recent arrivals, and these have been small (young) fish. I have also seen groups of Anostomus a couple of times. In all those, I have not seen much evidence of serious aggression (in the short period I could observe them). It is very possible that in larger groups the aggression can be prevented.
With Anostomus, the second time I have them (since ~3.5 years ago), I started with 3 fish, and one was quickly killed in aggression with the others. The two left fought without stop, so I had to find a home (gave away) one of them. The one left is my beloved jerk. He is currently in a mixed tank and has been behaving quite well (photo).
Would you post pictures of your large Abramites? Cheers!