LayzorBeams
Aquarium Advice FINatic
You're right about highly adaptable. In fact, they are among the fish known to gulp air at the surface due to low oxygen in their natural habitat, so they can survive in warm low-oxygen water. But they do prefer cooler water and aren't really adapted to long-term life in tropical temperatures. Keeping them in warmer water significantly reduces their lifespan. It's good that you've had one in tropical water for a year, but some people have also successfully had multiple male bettas in the same tank. Working in one situation doesn't necessarily make it a good idea.
In any case, 77 is the highest temperature I would keep one in; LOL lists their temperature range from 50-77. But african cichlids and botia loaches prefer it a little warmer than that.
IMO keeping multiple Betta in a tank isn't a bad idea as long as they aren't fighting a lot or injuring each other. It is odd and it really isn't recommended to try, but it isn't a bad idea for those specifics fish. For other fish it would be an awful idea. That isn't really the best example, IMO, because it relies on the attitude of an individual, which is a very varying variable. (Tongue twister?)
I think as long as the fish is living healthily, and to the best of our knowledge happily, and it is pleasing to its owner, then it isn't a problem. It becomes an issue when the fish is clearly bad-off. The fish doesn't necessarily care, it doesn't know its lifespan is shorter. Thats just for us to think about. I would be fine keeping it however i wanted up to the point of its quality of life being decreased.
Sent from my bed, the only space available to me that isn't smothered in dirty laundry or aquariums.