I have been keeping these since october i started with 7. Three i gave away due to aggression with each other and no space to keep them all. 2 were killed by siblings, 2 i still have in a separatted tank. i would not keep together i tried and failed they were 2.5 inches when bought in a 75 gallon and constantly after each other none stop. THere has been a salvini in with them since i got them and salvani has been the boss of them all only bullying the most dominant one of the pollenis leaving the rest alone, and have had a peacock cichlid in with them all most the hole time as well salvini does not bother the peacock, polleni harrases the peacock. the pollenis are funny only chase things that do not fight back they chase the peacock around madly then he gets sick of it and smashes them on the face and they run away like cowards, all bark no bite from what i see only bother there own kind. all mentioned fish were housed together. recently all are separated in different tank. others have seemed to keep together fine not on my end thow.