My panamensis get along well with each other actually. I ordered 6 and one of them came in as a "runt", under an inch while the others were all around 1.5-2". This little one was dead when I came home from a four day weekend, along with an equally small neet, but I suspect the Nicaraguan I had in there more than the other panamensis (nic was a jerk, I sold him last week because of this).
The panamensis chase each other a little bit but mostly they swim together. Maybe they are sticking together because they are not dominant... my tamasopoensis is the king of the tank and the sajica chases the panamensis around a bit. I also am not seeing anything resembling a pair forming. One panamensis is almost 4", and I'm pretty sure is a male. There is one more that is larger that I think is a male, then 3 smaller ones which may be female. My hope is to be able to keep those 5 in here together long term.