Hi, I have a 3.5 G heated and filtered aquarium for my betta. My issue is that my current heater maintains a temperature of 81.5° to 82° F. From what I have read this is on the high end of ideal for bettas. Am I causing him stress at these temps or is this still comfortable? Thank you.
I think he will be fine. Do not worry about that. Betta's can handle that and more.
I would personally lower it to 79. But your fish will be happy like that. I would worry more about giving him good water quality, hiding places, and a balanced diet of good quality flakes and live food like daphnea.