Loosing Fry Dont Know What Else To Do

[star4]

I had a lovely spawn of 170+ Rotkeil severum, they are now 12 days old, I started loosing fry saturday evening, but with so many in the tank I though some were just hiding, Sunday I went out for the day and upon my return was shocked to see over half "missing" Monday I transferred the remaining fry to another tank using water from another tank and some from the fry tank (about 10%) and cleaned out the filter in different tank water. I am doing daily water changes 20% but the remaining 20 or so fry are still dying. The are feeding ok and swimming about fine then they suddenly start spinning in circles then crash to the bottom, they do attempt to swim again but usually give up. Dont know what else to do?

 

[GuppyGoddess]

Have you been checking your ammonia/nitrite/nitrate?
What size is your tank?

 

[WILDER]

How many gallons is the fry tank.
Water stats.

Swimming in circles can be bad water quality, ph shock, toxins, overdose of meds, parasites, bacterial.