Is 28*C/82.4*F too warm?

[TokyoBetta]

The heater I use was previously maintaining a temp of 26*C/78.8*C, however the tank had a small air pump in it (the one that comes with it). I took that out yesterday when I did my water change because I deemed it as being essentially useless. It's not a proper filter and I read Betta's like calm water better anyway, and sometimes they even tear their fins playing in the bubbles.

My fish has now made this giant bubble nest, which I read means that they are happy with their environment. However the stillness of the water seems to help it retain heat, and now the water temperature has gone up to 28*C/82.4*F, warmer than last time.

What's the max comfortable temperature? If it goes up to X*C I should worry, kinda thing.

I also added a light recently and it runs quite warm. Luckily this has not affected water temperature but I'm worried that when summer comes it'll be too hot for my fish.

Room temp is 18*C/64.4*F and there are no sources of heat near the tank.

Thanks

[DefyingGravity]

My tanks are all at 27-28 degrees Celsius as well, and I've had no problems. We've recently had temperatures as high as 45 degrees (and our air con hasn't been working either!) and the tanks have stayed at the same temp. If you find the tanks getting hotter during summer, try dropping the heater a few degrees to combat that.

Also, I wouldn't go over 28 degrees c, just to be on the safe side :)

[1fish2fish]

82* is the ideal temp IMO.. I keep all my tanks around this temp. IME it brings out the colors of your fish best and keeps them active. The higher temp is also helpful at keeping bacteria away as many pathogens can't survive in the higher temps.

[TokyoBetta]

Thanks, he seems quite happy so hopefully that means hes enjoying the hotter temps.
But is there a max temp at which a Betta would, as it does in cold water, fail to thrive and become ill?
If I come home one summer and find the tank sitting above a certain temperature, say 84 or 86*F, then should I be worried?

[1fish2fish]

Personally I wouldn't let it get over 86*F just to be safe but I've been told some bettas have been in tanks up to 90*F without problems.. it really just depends on the fish. Basically if you see your fish starting to blanch (get white) or start behaving oddly you may want to lower the heater. I think keeping the temp stable at anywhere from 80*-82* with 86* being your absolute maximum would be safest.

[TokyoBetta]

Thanks, I will go with 86 as the max for now.
I am definitely going to look into a higher quality heater before winter is up, something that's at least adjustable to a certain degree. The one I have isn't el-cheapo but it may be a little to simple for my peace of mind.