When I put 8 Tiger Barb in my tank of Silver Dat (Polotas), the Barbs were about half the size of the Dats.
In less than 15 mins, the Dats hunted and killed 2 Tiger Barbs and I had to move the remaining 6 Barbs to another tank..
I am a bit surprised how your Dat is not eating those little Barbs.
Cheers,
Sid
PS: I moved the 6 Tiger Barbs to a tank with baby (4-4.5") Bichirs (Endlis and Delhezis). They lasted all of one week in the Bichir grow-out.. There are no barbs left now..:S