Temperature Mistake

[presto]

Hi Everyone,
I have been keeping my 20 gallon tank at 27 degrees for the last 7 months. I recently did a water change and the tank temperature became too cold(tested my new python system) so I increased the temperature on my thermometer by turning the nob just a touch. I have just come home to find the tank is at 35 degrees!  I think it has been this temperature for at least 2 days.

I have just done a water change and brought the temperature down to 30 degrees for now but my fish have been panicked for hours now.

My questions are
1) Are my rummynose tetras, red-eye tetras, ottocats, and sterbai cory's permanently damaged. I heard you can sterilize fish at high temperatures.

2) Is there anything I can do to help them recover from the 8 degree change up and down over the last 2 days?

3) Any suggestions on a moderately priced heater that doesn't fluctuate 8 degrees from a small adjustment?

I appreciate any advice the forum can offer me.

Thanks,
Chris P.

[Aquaviewer]

Hi Everyone,
I have been keeping my 20 gallon tank at 27 degrees for the last 7 months. I recently did a water change and the tank temperature became too cold(tested my new python system) so I increased the temperature on my thermometer by turning the nob just a touch. I have just come home to find the tank is at 35 degrees!  I think it has been this temperature for at least 2 days.

I have just done a water change and brought the temperature down to 30 degrees for now but my fish have been panicked for hours now.

My questions are
1) Are my rummynose tetras, red-eye tetras, ottocats, and sterbai cory's permanently damaged. I heard you can sterilize fish at high temperatures.

2) Is there anything I can do to help them recover from the 8 degree change up and down over the last 2 days?

3) Any suggestions on a moderately priced heater that doesn't fluctuate 8 degrees from a small adjustment?

I appreciate any advice the forum can offer me.

Thanks,
Chris P.

The good thing is that you caught the problem and all your fish are alive.  Most of the fish that you describe can handle elevated temperatures over the short term.  In fact some medical treatments suggest elevated temps as high as 35 (not suitable for all fish of course). As for sterility, I can't say for sure, but its unlikely.  Temperature fluctuations would have more of an impact on fry development, affecting sex ratios etc...

As for bringing the temp back down, just do it gradually to minimize stress and your fish will be fine.

Jager all the way.

[presto]

Thanks Aquaviewer,
I will bring the temperature down slowly. I'm glad that my fish can handle the heat naturally, although I'll make sure they don't have to from now on.

I just bought a new 100W heater with a safety shut off and backup thermostat included. A guy at the store I go to says my thermostat broke so the heater didn't know when to shut off. I was using my friends old "elite" heater, I hope this new purchase will prevent this from happening again.

The fish seem to be recovering.

Take Care,
Chris P.

[fishycanuck]

I agree - used heaters are false economy. I had a fish boil like yours a few years ago. 

[KLKelly]

What kind of heater comes with a backup thermostat? 

[presto]

What kind of heater comes with a backup thermostat? 

My last statement was a bit misleading. It has a temp. sensor which reads from the glass but it also has a small metal strip, which to me , looks like another sensor, and the automatic shut off to prevent overheating. It is a Fluval 100W Heater. I'm testing it out today and will see how well it worked when I get home tonight.