10 Gallon Tank Problem

[deeh]

I have owned several fish tanks and currently have three, one three gallon betta tank, one 35 gallon tank and several months ago added a 10 gallon tank... I have an epi test kit and clean the gravel and tank once a week.  Friday I fed all my fish turned out the lights and headed out of town, when I returned on Saturday afternoon, all the fish in the 10 gallon tank were dead, one fish remained he had what looked like skin peeling around the front of his face, this tank had 3 mollies and 3 tetras.
 
I cleaned the tank a day early put in some aquarium salt for stress, this a.m. he was floating...
 
any suggestions
 

 

[Byron]

The quick answer is that something was in the water that severely affected the fish, so let's find out what it might have been.
 
Can you explain how you "clean the gravel and tank" each week?  Be specific.  Do you use any additives, such as water conditioner (if yes, which one)?  Is salt added regularly, and how much if yes.  How much was added yesterday?  And which fish is the "he was floating"?  Was anything done prior to the Friday?
 
Byron.

 

[StevenF]

Maybe your water heater has failed and the temperature is not correct.  Or maybe the filter pump has developed a short to the water?