I have been keeping african cichlids for 15 years and as far as I have ever seen demasoni can be the most evil little buggers out there. They are best kept in groups of twelve or more and will readily kill off competitors for territory and mates. I had a group of 20 of these along with 20 electric yellows in a 125 and had many sucessful spawns. Then one day my dominant demasoni male went on a murder spree and killed 8 yellows and 5 other demasoni within 48 hours. I took him out of the tank which really upset the heirarchy of the tank and caused mayhem for around 2 weeks. They are beautiful fish however the agression level was enough that I decided to use the tank space for another species.