Keeping fry alive

Hi,

I had about 15 aulonocara fry that I stripped from the mother and
placed in a 21L tank. (I kept the mother in the main tank not the fry
tank)

The fry tank has a heater and a filter on it.
the water levels are all fine 26-27deg celcius 8.0pH nitrates and
ammonium is fine.

However my fry are dropping dead daily!

They seem to be eating ok.

One thing that may be of a concern to me is the flow rate of the filter
may be too strong and might be causing the fish to swim too much
against the force of the filter????? i dont know if i can slow the rate
down???? it doesnt seem to have any knobs or anything on it.

I am feeding the fry crushed veggie/spirulina flakes.

Any help would be appreciated.

Andre