Question
This winter we kept our fish in our pond as usual-the temperature got to be about below zero.We have never lost fish before,but this winter all have practically died. There seems to be like a white fuzz substance on them. We are distraught as we have never seen this happen before. We live in Ontario-Any help you may be able to send us would be greatly appreciated, And is there any way we may be able to save the remaining fish.  

Answer
I'm so sorry about your fish loss.  Someone else contacted me today that lost all their koi.  In there case, I suspect low oxygen levels in the bottom of a deep pond.  in your case, you saw white fuzz which is probably fungus.  What size pond do you have?  What kinds and sizes of fish?  I suggest doing a water change (up to 30% or so or as much as you can manage safely), adding pond salt to 0.5% which is safe if you have plants but deters fungus, and probably adding a pond fungal medication.  I avoid using such strong medications if at all possible but if you've lost fish, and they have white fuzz, that's pretty bad fungus.  Cleaning up the pond as soon as you can (getting debris off the bottom, cleaning and starting the filters) will also help.  Fungus normally attacks weakened fish or when the water is not in good shape (dirty pond, etc.).  I hope things improve!

Robyn
fishpondinfo.com