I noticed one very small whit spot on one of my Cardinals a week ago and thought it might be white spot so kept an eye on it over the next few days and decided it wasn't.
now i have had 3 cardinals die over the night, one i found still siting on the bottom in his last moments. I have done water tests for ph 7, Ammonia 0, Nitrate 0, Nitrite 0
ok so the questions are;
If it is white spot will there be any evidence on the body once they are dead?
What else could it be? there doesn't seem to be any damage or injures to the fish but there gills are red.
Could it be not enough Oxygen in the tank? it is a planted 200l with one co2 diffuser running.
Or something else in the water i cant test for?