Sae similar Kallopterus ...

Hi all,
Yestarday I went to my fish seller to buy some other Siamensis (I have 
just one old, 2.5" lenght, all silver) and he sold me some little one
(1") but (for me) very similar to Kallopterus . He showed me photos of Sae
and Kallopterus explaining that are similar (grey, with yellow fins and
a dark line from head to back) and he was always furnished as Sae. 
I lurked on digest about all Sae informations, or pictures and now 
I am confused. May somebody teach me some how to be sure to buy
Sae babies and not Kallopterus ones.
Thks & rgds  Ezio
  FERRO Ezio   Phone #  + 39 11 6848230
  Software developer        C O M A U  S.p.A.
  Strada Borgaretto 22    Borgaretto (TORINO)  ITALY