The adult colour of the purple labeo and the variegated shark or Harlequin shark are practically identical, (purple Labeo background colour may look more grey where Harlequin color background colour is jet black), as are their size and behaviour. Hence they are easily mixed up. However the Harlequin or variegated shark are great fish, but easily bought by unsuspecting fish keepers at a mere 2-3" when they look stunning and completely different. Then they have a beautiful mottled black and gold colour. Then they grow, and grow, losing their gold and gaining more black as they do, and when they get around 6" you have a totally black fish but with the beautiful red and purple on each scale.
I know this fish as Labeo Variegatus which was reclassified as Labeo Cyclorhynchus.
Labeo Congoro I have never seen for sale and equally have never seen small so do not know what colour they start out, do you Victor? Would be interesting to see if this was originally one fish which through biodiversity changed habits and eventually led to two classifications.