You might not see the dead fish until a day or two later. Typically fish don't have enough air in their swim bladder to make them float, they are neutral buoyant. Only after a period of time when decay starts to set in, and gasses build up do they float.
It could be that the CC are starving to death too. Not a lot of natural food in the pond yet. Try feeding asap and see if that slows down the death rate in the next 3-5 days. Do they look skinny?
