To cool the water down, one way would be a partial water change, switching out just a little at a time every hour or so to ensure that the temp doesn't drop too much too quickly and letting him acclimate to the new temp. Why is the temperature so high? Can you tell us more about your tank --- size? heated? just the one fish? location?
If you can avoid flakes, pellets are much better. It's partly that pellets are easier to remove if uneaten and partly just a nutritional thing. Flakes are more like potato chips.
If the thermometer is not working properly..how are you finding out what the temp is? are you sure it's that high? and when did you notice..was it recently..if he is at the bottom, maybe cuz the top is too hot..not sure.. but yea take him out.. and change the water, and condition it, but now because it's been so hot..do not drop the temp too low..too fast, it will shock him..try to add a few drops in a smaller tank, like a kritter keeper if you have one.. and then take some of the water from his tank..leave in the kk..then add some of the cooler water a very lil at a time.. until you get the 78d temp..but you will need a new thermometer.. to watch the temp..because you don't want him to go from too hot to too cold.. it's gonna be a lil difficult..but keep close eye..and until you also have a new heater if that one is defective..you cannot keep him in the tank with that heater on.. Hope all works out for your lil guy..I know what it means to make sure you do all you can to help your fishy:) Good luck..Keep us posted..
If the high water temps are because of high outside air temps, try using a fan to blow the air above the tank water (if you can without risking a jumper). If my information is right, doing so should increase the rate of evaporation, which will cool the water down. We've been having outside temps of ~90F outside, so inside my apartment (without AC), it gets close to ~95. I've been able to keep my tank temp at about 84F consistently with the use of a fan.
I know ice cubes made from conditioned water work really well, and my CT loves them, but they are risky. So, just be warned. Adding one every hour or so along with the fan may help bring the temp down more, and kind of safely, but don't quote me on that.
Lelei: It doesn't sound like Eveh's thermometer is broken, it just sounds like there's a green colored "safe" zone labled on it, and the temperature is way above that. Both of mine have that.
Icecubes cool the water too fast and don't provide a lasting solution. A fan over the surface of the water would be your best bet. If you have the tank in sunlight, that's not a very good idea. If your heater is the problem, you might want to get a new one that you can set for certain temperatures.
Ok, so my heater isn't on. We have the AC on 24/7 (in the middle of a drought (over 90 degrees too)). Over the night the temps dropped because the lights not on, that might be why. No clue about the temp. No the thermometer is NOT broken and the size of the tank is 2.5 gallons and he is my only fish... in there o.o Sometimes he goes up and swims but sometimes he also goes down. I can't feed him pellets (well I can TRY) because he takes a bite spits them out. He's done this a lot but now he only does it one time. But NOW he doesn't even TRY. We have Wardley pellets and it's the best I can get. I can go to a local store to see if they have something else but my dad has the truck. I've given him 4 flakes a day (two morning 2 night, same as pellets) and he eats them right away! I'm just worried that flakes aren't enough. And I want Oddie to be in best care and health as possible. My parents think I'm over-reacting on this fish. They just don't understand o.o
Hello Evah..I understand..yu want to do a that yu can for yur lil guy..I have noticed a lot of ppl who use the Wardly pellets..say thier bettas..dont like em..mine did not eat those ones either..and as oon as I switched to Hakari Gold I saw immediate improvement..he did not spit em out..and now hes just ravenous for them..If u can try them. Or also I hear soaking yur pellets in garlic juice..might help..worth a try..good luck pls keep us piosted:)
Ok so I just fed Oddie 2 Wardley pellets. I put them in his and and he nibbled at the 1st one and floated to the filter stream and was pushed along which drew his attention. He ended up eating the 1st and 2cd one I also did some water change and put conditioner in. He seems fine and is swimming around normally. I don't see any bubble-nests on the bottle cap though.