Originally Posted by Xeek
Have you tested your water? If so, what are the following parameters?
Hardness: 0 dGH (Don't have a KH test)
This doesn't bother anybody else?
If you are noticing the white stuff AFTER death, it is probably just fungal decomposition. If they are getting it before death, then it is probably columnaris.
I'd be more concerned about your water parameters. Where are you getting your water from? It looks like it's being run through a R/O unit or a water softener. Without replenishing natural ions in the water, it's not good for fish or even people to drink. (Essentially this sounds like distilled water)
With a hardness of 0 dGH, there are little or no natural nutrients in your aquarium for your fish to live on (stuff like iron, magnesium, etc.) that both your fish and you as a human need to live. Your KH is probably low as well, which will give rise to pH swings.
Your pH of 8 is fine as long as it stays like that. I've had fish live in pH of 8.2 at my apartment at school.