Yeah, and it is!
https://gfycat.com/JubilantWeepyApisdorsatalaboriosa
This was my setup for a long while. 4 seemed to be the minimum magic number. Aggression was spread, no one ever really fought or fin nipped other than the liplock when a new one was introduced. I had this for a while but eventually traded 3 off to try something new.
From talking to others and first-hand experience, it does seem that all male american cichlid tanks can work. They just need space, minimal decor so they won't get territorial, and of course, some luck with personalities.
I seen a guy on here post his setup with 4 green terrors in a 75. They were all pretty much fully grown and he never had issues with them...
