Think I'll join in this conversation.
Here's what I've found: Different species have different temperature tolerances. Different sizes of those different species have different temperature tolerance. Those species have different lower lethal dissolved oxygen requirements. For example, Big gizzard shad can't live in water much below 4 ppm DO, but can tolerate temperature into the 90's. Largemouth bass, especially bigger ones, can't tolerate temperature consistently 87 or higher...they have to have a refuge. One study on a lake I've helped manage proved bass in that lake would stick their noses into the thermocline, where DO was about 3 ppm and temperature was in the high 70's, during the hottest months of the year, when surface temp was 90+, and 83 just above the thermocline.

Here's my response, based on decades of doing what I do and studying fish behavior. Largemouth bass are distressed when water temperature exceeds 83. If consistently above 87 for an extended period (a week), the bigger, older fish begin to die.

I've had several lakes under management in Texas where we saw that phenomenon firsthand. Had one client, in particular, who bought an aeration system from a vendor, had it installed, liked it so much he decided to add another one just like it. (The first one was sized exactly for this 10-acre lake.) So, he had twice as much as the lake needed. I bet the lake was turning over 3-4 times daily, at least. One hot July morning, he rang my number. "Seeing two or three big bass floating today. Why?" There wasn't enough logic to give him an answer. Then, it happened again, then again over the next few days. The lake was three years old, loaded with fat, young, healthy feed-trained bass that were two years old when he stocked them at a pound and a half, average. Water was fresh and healthy, visibility was 30+ inches, no toxic bloom. Fish fed well, behavior seemed normal, except feeding activity had dramaticall slowed. I had him get a thermometer and begin checking temperatures all over the lake in 2-foot increments. The entire lake, top to bottom, was 87 degrees. I had him turn off one of the systems. After three days, no change...and a few fish were floating each day. So, I had him put the remaining aeration system on a timer from 10 pm until 9:00 a.m. Within four days, the temperature dropped to 83 degrees and fish stopped dying.

I've seen this phenomenon happen over and over with Largemouth bass. It happens with bluegills to a lesser extent.