I lost a VT a few weeks ago, and have been wondering almost daily what the cause was. I will try to explain:
I had 2 - 1gal canister jars sitting on a shelf at my desk at work. They are about eye level, and I truly enjoy watching the boys during the day. They are, of course, alone over the weekends. One VT and one HM, both doing quite well. I kept the jars separated by about 6".
I bought a new VT and a CT, and added two more 1gal jars. They were close together, by a few inches. The two VTs flared like crazy at each other, but when I moved them around, the VTs didn't flare at the CT or the HM. Those two guys, Jessie and Ragnar, just dance around and want to eat. The two VTs, Steve and Flokie, were more interested in flaring at each other. Now I have very distinct personalities here with these four boys.
On Friday I changed out 100% water, treated and fed. Without thinking, I left the two VTs next to each other, the jars practically touching.
Monday morning, both the VTs are in distress. Jessie and Ragnar are their usual hungry selves, but Steve and Flokie...well, Flokie's gills were pumping very hard, his color was ashy, and definitely swollen under the gills. He just hung in the water looking awful. Steve sat on the bottom, gills pumping hard, also swollen, not eating. I immediately separated all the jars and changed the water for both VTs. I'm pretty good at water changes, and the temp rarely is off by more than one or two degrees. Tap water conditioner every time, the same every time.
Flokie died shortly after. Steve took most of the day to return to normal. He ate a few pellets before I left. Next day he was fine, as was the other two.
My question is (after all that, sorry) is can male bettas flare so hard for so long that they can stress out and die?