Pseudotropheus Socolofi are a beautiful powder blue cichlid. They are somewhat aggressive, but mainly towards thier own species. I have 6 of these, and 2 fry gowing up in a smaller 5 gallon tank. They give the tank a really nice splash of color. They tend to chase around the smaller fish, but other than that, they are pretty docile.
Coloration of the fish are identical in both sexes, like a lot of the cichlids I seem to have! :) Just like the demasoni, the males of the species are brighter and bigger, but not by much. The males also tend to have more black on thier dorsal fin. Of any species, this is probably one of the few that you can get away with having more than 2 males in the same tank.
John Carr's African Aquarium