Chocolate Cichlids in general are very peaceful, they actually do very well in a nicely planted tank with larger tetras ie Columbian Tetras etc... When a pair does spawn, they aren't overly aggressive towards other fish yet can be VERY aggressive towards one another... when they are not in spawning mode tho they are very good with one another generally speaking. The male is normally the one to pack the punches out of the pair, so it is normally the female that ends up tattered. However, she can hold her own also and give as good as she gets. They certainly are harder to breed than alot of cichlids... and I have found that the drop off rate of fry is normally more so than other cichlids. A single Choc on his own would be fine and dandy.. it's aggression towards one another than can be the problem.