Sexing Black Belts?

[Spishkey]

does anyone have any pics to distinguish the difference between young black belt cichlids?
i know when they are older you can tell by markings and colourings, but i have 7 here from around 5 to 7 cm, and they all look different!!!!
any ideas ? would try and get photos but they are moving far too fast and hiding still!

 

[Spishkey]

no one keep these??

 

[Cichlid_Crazy]

i have a Argentea...not a clue on sexing Vieja tho...sorry mqte...never seen a black belt or any other Vieja in real life...thats why i quickly snapped up the Argentea when i did