I've never noticed this before, but I suppose I haven't seen too many older P. acei and the largest I have at the moment are only about 4.5", and he's a little over a year old. The other fish I mentioned are at least 5 years of age.Actually Acei get much larger than others and not just in the tank. Most profiles say they will only hit 6 inches, but I often see them at the 6 inch mark and larger. I had a white tail that was 7 inches. You may see other mbuna get over their normal size, but I see far more Acei that do compared to other species.
I always thought this classification was odd too, the same with the classification of Pseudotropheus livingstonii, another sand dweller, although P. acei rarely frequent the sand habitat as often as P. livingstonii does. I think the Hap/Mbuna classification is becoming too dated. Sorry to retract from the original purpose of the thread.Acei are not like other mbuna, in fact I am not sure why we classify them since their behavior is so different. They school and swim in the open area not sticking to the rocks like others. Genetically they may be the same, but behavior they are different..