Hot discus

I have a 60 gal tank I keep at 81-82F with 5 discus plus a few other
assorted fish. The other day I noticed that one of the discus was at the
surface partly inverted with his(her) mouth gasping. the other fish
seemed to be breathing harder than usual. The room temp was 24C (the A/C
uses metric). The tank temp was about 86. The lights seem to push it up
during the day. I got a bubble disk and a pump from my LFS. The fish
recovered within 15 min and the temp slowly dropped to normal.
I guess the heat drove off the O2 and the air restored it plus the air
cooled the water. Hope this can help someone with the same problem.