Why Are My Neon Tetra Dying?

[Enna]

Tank size: 165 liters
pH: 6.3
ammonia: 0
nitrite: 0
nitrate: 25 (tap water is 20)
tank temp: atm 31 as I'm treating a hatchet with whitespot

Fish Symptoms (include full description including lesion, color, location, fish behavior): Two days ago one of my neons looked listless and quite, kept out of the way of the other neons but could swim fine, he looked bloated, not lumpy more like he had been inflated all around even his back, he opened and closed his mouth very rapidly, his red stripe faded a little (blue stripe fine) then overnight he died, then another has just been through the same and died today.

Volume and Frequency of water changes: 10% once a week

Chemical Additives or Media in your tank: nothing added, I have raided the tempreture to 31 as one of the hatchets had whitespot, on Friday it will have been that high for 10 days, the spots have gone but want to give it an extra day or two to be sure.

Tank inhabitants: Corys, shrimps, congo tetra, silver hatchet, blue rams

Recent additions to your tank (living or decoration): none

Exposure to chemicals:seachem prime and flourish on water change days

 

[N0body Of The Goat]

Having the temperature so high can cause dissolved oxygen problems. An extra powerhead rippling up the surface can help resolve this.

 

[k.o.d]

Agree with the above, higher temps mean that the O2 content is lower, easily remedied by increased agitation of the surface.
Neons used to be prone to the aptly named 'neon tetra' disease that caused similar symptoms, but not having kept neons for many years unsure if that is still prevalent.
10 days at that temp will easily have run through the whitespot cycle (the time decreases as the temp increases) so maybe time to drop the temp, and I do wonder why you have not added a whitespot treatment as 31 degC will not neccessarily kill off the spores.

 

[Enna]

Thanks for your replys, I am dropping the temp back down again.

I did not add whitespot meds as after reading some of the threads on here about ich some people use only heat to treat it successfully. I want to try to add chemicals only when necessary and if the whitespot had not cleared up with only heat I would have added meds. I'm sad to have lost two of my neons and in future will reconsider wether to use this method or not. It took a good seven days for the last spot to go but its all gone now (hopefully). The rest of my neons are looking ok, I'm really hoping I don't lose any more