Hey Ivan,
Yes, I think it was the lack of O2 that was the result of me being away for a few days and not being able to do a water change to regulate the Temp (cool it off). It's been in the triple digits where I am and when I got home my temp was at least 90+ Deg. Even w/the the immidiate water change the day I got back and there after I think it was too late as the internal organs of the TIGS was already damaged due to lack of O2.
The 3rd one seems to be doing fine and the bump/swelling is reducing ? perhaps he more tolerance and hopefully will pull through.....I'm still crossing my finger...

It took you a while to tell us this critical part -![]()
My fault.same here.. california is hitting in the 100!!! it's too hot. i need to open the aircon for almost 24 hrs a day. and my tank is still at 82-83 F. it's just too hot!![]()
i would try to get some air inside. if possible a temp reader and an industrial fan to move the hot air out. if their was such a thing as auto on when temp goes up at 80F in the room that would be good to have. my house goes up to 90F upstairs and maybe around 85-86F downstairs and this produces an 83F on my tank temps. as even when i get home and open the aircon and try to lower it down at 78F inside the house the tank would just go down to 82 im lucky if it goes down to 81F. i'm planning to get some heavy duty air pump for my 180 to boost the oxygen in it.
i doubt it was temeprature
HIGHLY doubt
those fish should be able to handle a temperature of that level for a short period of time
if in fact your tig died from lack of O2 then your other fish should have died as well such as the ATFs. but this isnt the case.
tigs dont need THAT much oxygen in there water, they have the same o2 requirements as most other south american river fish that we keep.