might i add he is super aggressive and will probably kill any tank mates i have tryed in larger tanks but moved him to his own he has killed two other african cichlids one a jewel and the other a mbuna
they grow to be around 5.5 inches, and I think they like a bit of swimming space. Perhaps some more room would be appropriate. I'd want it to have about two feet to swim. Alternatively, this might be the moment for that huge tank, where he would be the smallest fish?
At least a 20L, if not something around the size of a 29. Really, it's what you can afford.
Jewels can be unpredictable. But I would get him some dithers that aren't threatening. Most of my aggressive cichlids ignore dither tropical fish (like tetras), but zero in on other cichlids. If this fish is used to living by itself, it won't like the sudden addition of other fish. . .