Fish Sitting Disaster

[dcfeeiv]

my friend is studying in england for the fall semester and i offered to watch her betta for her
she stopped by my house while i was at class today to set up her tank and put her boy in and make sure he was happy so she did only she put the tank right infront of the window and it got up into the 90 degrees F and i want to take it down atleast 10 degrees prolly closer to 15 degrees whats the best way to do it?
i already moved it and un plugged the heater
could i float a sealed bag of ice in it? or should i just do a water change or what?

 

[WILDER]

Don't fetch the temp down by more than two degrees, then let it cool down naturally.
If the betta on its own add some salt for the stress.
Look out for whitespot, swim bladder, and columnaris.

 

[WILDER]

http/www.aquariumlife.net/articles/aquarium-care/101.asp