Found this on Aquatics Community:
Tank Buddies: They are very few fish that can be placed with Red Jewel. Generally the Red Jewls will accept peacock cichlids, same sized mbunas, or haplochromis African cichlids. They are very aggressive towards New World Cichlids such as a Green Terror, Smaller Dwarf Cichlids, Jack Dempseys, etc.
Aren't Demasoni and Yellow Lab Mbuna?
They are mbuna. This is not good advice in my opinion. My experience with the jewel cichlid species I have kept is that they are relatively passive until they start spawning at which point they become very territorial towards other species. Since you have a lone fish my expectation is that you risk it being outcompeted and possibly beat up on. Especially as you add fish and safe territory becomes harder to find.
Keep in mind, there are actually a bunch of different related fish called "Jewel Cichlids" which don't all have the same temperament so it is a bit hard to know what you are going to get from a temperament perspective.
I want to be clear, it is not impossible that this will work for you. However, when you mix territorial fish from drastically different environments with such different behavioral patterns it will fail more often than it will work.
Yes they are.
People put Jewels with Mbuna all the time.
People put clown loaches in 10g tanks all the time.
People put goldfish in bowls all the time.
People put large volumes of fish in uncycled tanks all the time.
Doesn't really make it a good idea.
Have you done this yourself and had long-term success(for more than a year)? What is your basis for your strong opinion here?
My concern is that sometimes things will work in the short-term but not the long-term. It is possible to see a tank that looks like it works for a while before it all falls apart. I have seen people throw mbuna into a peaceful community tank with tetras. Sometimes it works due to the specific fish involved. I still wouldn't recommend it broadly as it will not work the majority of the time.