20G - both my clowns gone over night :(

[Aine]

I had a purple firefish that died very suddenly, probably from fungi.
It's something fish can have for weeks before it attacks them and show in their behaviour. Then they die very quickly.
I had seen a strange behaviour for about an hour before he died, though. You might have missed it in the night.
The rest of my fish are doing great... I battled ich not long ago, and won 
I don't know about your tank's temperature, though. Maybe I missed it. But maybe it was too warm... I've been adding froze water bottles to my sump regularly this summer, because of the heat.
Or the water you've been using?

Anyways, good luck with your next fish!!!