Isn't a 4 x 2 tank too small for the larger upper jaws and for lower jaws? I have a 3' x 18" tank and it is definitely going to be too small for the Teug and right now I feel like even my Del is getting close to pushing it for swimming space, and she's only 10.5".
Can't picture it being great to have a 20 inch fish in a tank that small.
I would think it would be better to have more of the smaller UJs. Like Senegal, Delhezi, Polli, Palmas, Mokelembembe....
I think Severums would be a good cichlid choice!