They act the same way as they do in water that's too cold. They will get lethargic They will stay near the top of the tank to breath. You will notice them panting. Try to keep them in the shade in the coolest part of the house. Put a good thermometer in the tank and keep an eye on the temp. In drastic heat a water change would be good but only reduce the temp by no more than 2 degrees in a 6 hour period. Water changes of colder water will send your guy into shock, and you will run the risk of Ick and fungus infections. Not to mention Death.

 

I had a heater malfunction last summer while I was at work. I have AC so I continued to use heaters in the summer since my apartment was probably around 70 degrees, which without a heater would put my tanks at 65 (since water is usually 5 degrees colder than the room).

Anyway, while I was at work one of my older heater's malfunctioned/broke and started to heat the tank like crazy. I'm not sure what temperature my tank go to since at the time my thermometer when to 90 and it was showing a reading of 90 so basically who knows how hot it actually was. I came home to find my fish darting around the tank like crazy and panting. I quickly cupped her to get her out of the tank and put your cup in one of the tanks that was at 80 hoping to slowly bring her water down to normal.

unfortunately, she didn't make it through the night.

 

I have been the same route with heaters. I have found a few that have worked well for the past couple of years. I change heaters about every 2 years just to stay on the safe side. I have found over and over that the quality of some of the best heaters made (for that matter any product today) is almost non existent. I have always used Marine land heaters but when I bought one 3 weeks ago to cycle a new tank. The heater I set at 78 degrees stayed that way for about a day and than started to climb to 90+. I set the heater back to 74 and the temp dropped to 83. I again reset the heater to 70 and now the tank stays at 78. (go figure) I contacted Marine land ( the heaters are a life time warranty) The are replacing the heater but I haven't received it yet.
When you cupped her and put her into a tank that was 80 degrees The stress and shock is what did her in. It was to rapid for her to adjust. if this ever happens again cup it in the same water from the tank and let it sit for a few hours and that accumulate her (or him) as you would a new fish from the store going into the tank for the first time. When a shock like this happens it is always a good idea to slowly bring them back keep them in a very low light situation, and wait and see. (The wait and see part is the worst part.)

 

I just floated her cup in the tank (cause the tank was holding another betta) i didn't actually put her in the tank. The only reason why I did that was because my apartment was freezing at the time I felt leaving her in the cold air would shock her more.

 

And you were right to do that. But You know by the time you found her the damage was already done. It doesn't take long to injure a fish in this fashion. Basically she was cooked from the inside out and was just in survival mode. doing what she could to keep moving and trying to swim as fast as she could to reduce the heat, which really didn't do her any good either in overtaxing her heart and other organs. we do what we can at the time with the knowledge we have and learn from our mistakes. We don't try and harm any animal, and we try to make their life a little richer and ours even more so because we have shared our best with them.

 

I mean I knew there was a good change that she wasn't going to make it but I wasn't about to just like give up on her. I want to try to at least save her.

 

never give up until there is no pulse. I have never given up on any animal. We try, we learn, and we do everything we can. I find Praying helps, and some times that's all that gets it through.