1st suggestion is I hope those fish weren't in the tank during cycling? With mbunas you want to stock groups of young fish all at once, ideally. Eventually getting 1m:3f minimum, more females if possible.
The demasoni are an all or nothing type of fish needing 12 or more to a group and a species tank preferred, especially at 60g. They are very aggressive. I recommend trading that guy in and going for other less aggressive groups to give you the colors you want.
With Mbuna you are looking at territory area so the footprint is what determines stocking levels. With this footprint I would go with 3 species of smaller, less aggressive mbuna. Aggressive is a relative term here, all mbuna are aggressive of course. My suggestions...
Yellow labs are an excellent choice of course. Stay small, great colors, high success rate for keeping and breeding
Yellow tail acei can work in a 4ft tank but having had them myself I would want a 5ft+ for them if I got them again but I highly recommend them anyways. They can get big at 7" and are very active but mine were the most peaceful fish in the tank and full of personality.
Rusties stay small, add purple, orange and brown and also pretty chill for mbuna.
These three give you almost every color and keeps your aggression down, a solid selection IMO.
Avoid - Demasoni, bumblebees, socolofi, zebras and so many others lol. Also avoid adding groups of similar fish.