How Warm Is To Warm?

[Night61]

after discovering that one of my new fish have brought Ick into my fish tank, i have begun treatment on the tank. part of the treatment was raising the tank temperature.
the tank went from the mid 70's to 86 degrees. since raising the the temp i have lost two fish, a barb who i was suspicious it was ill but never new what it had, and now one of my brand new Priscilla tetras is on his or her way out. now all the fish that have been sick have come from one particular fish store which i will not be returning to for a while.

my question is the increased temperature causing these death or increasing the illnesses that this fish had, that i was unaware of.
btw i am treating with Ick attack a natural med to protect the snails.

 

[drobbyb]

Usually you are supposed to increase aeration since warm water carries less oxygen than cold. Some medications for ich will state this.

Are your fish gasping for air at the top of the water?

 

[england]

how quickly did this temp rise happen, that is quick a jump if it was quick

 

[Night61]

temperature was raised overnight.

i have lots of aeration one of my ornaments, plus my filter has and aeration part of the filter as well.