If the ventral/pelvic fins are blood red, than it is probably Aulonocara Cobue. If they are blue, with a hint of orange stomach, it is probably Aulonocara Mbenji. If they have a bit of yellow they are probably Aulonocara Masoni. They all get about 4-6”
Of course, there is always the strong likelihood these days that they are actually Aulonocara Mongreli.