So we all agree that bettas do well when kept in temps of 78-82. I am not going to argue that. And I am not going to talk about lower temps because I know that they are tropical fish that need warm water. But why 78-82? Why not warmer? I know that the shallow waters where bettas originated get hotter than 82, and I know that members of this forum have kept fish in water that has gone into the 90s because they were kept outside. I have kept my fish at 82 for a couple of months, sometimes the room gets warm and it creeps up to 84. They have never seemed to mind this at all, but when the water dips to say, 76 as it did yesterday after a heater malfunction, they acted sluggish until I brought the temp back up.
So where does our knowledge originate? And how hot is too hot for our fishy friends?