I recently re established my sorority a few days ago due to a rotten plant bulb from Petco causing a massive ammonia spike that killed my last one... after removing the bulb and seeing the Ammonia was down to 0ppm, i added a sponge filter for extra bio filtration and added a *single* female. She thrived and after 2 weeks I added 6 more. The female that was there showed hardly any aggression to the others and 4 of the 6 I got seemed pretty chill. However, I had 2 larger females, much much larger than the rest. They were about the same size and were at each others throats, but stopped fighting after the 3rd day. I concluded the pecking order had been established... however, one of those 2 was found dead just a few minutes ago, she was almost wedged into a piece of rock, her find all torn and ragged... the other female now lays semi-lethargically in an arch under some rock work. I say semi because she reacts to fish that swim by, and goes up for air every few minutes or swims around a bit just to return to that spot. My ammonia and nitrites measured 0ppm and nitrates <20ppm. I’m freaking out because I don’t want it to be some horrific betta disease. My best guess is since the size difference between those 2 compared to the rest of the girls was so big they found eachother as the biggest threats, and they finally had an all out fight and the larger females fought so hard one died and the other is wounded however the other does not have any fin or body damage that I can make out... my parameters are perfectly fine as you can see and the other bettas are doing perfect, so does anyone agree with my hypothesis or perhaps know what else could have happened? thank you so much for those that respond.