It won't matter who it is, they'll all pick on the dead ones. Sorry for images, but dead meat is food for them no matter what or who it used to be. Even if you feed them, they'll keep eating.
I don't think one girl killed another, you would have seen the aggression even if it was flipped on a dime, that one would still be aggressive to others now. So it looks like your girl died of unknown causes and then the girls just ate from there. :-/
I think nearly every fish will eat a fish that has died. I have found several half-eaten corpses in my tanks over the years.
Fish are opportunistic feeders. They don't know that they are in captivity and they are guaranteed regular feeds, so they take whatever they can get when they can get it, whether that is pellets or a dead tankmate.
You can't do much, all you can do is prevent further deaths.
I think you should just leave them be, check on the fish every hour and check every single one closely; excluding the time you sleep. Keep note on any weird behaviors, I think we can all learn from this.
Good luck, I hope you find the reason that this happened. :I
Don't feel like you've done anything wrong. Fish die for all sorts of reason, not just because of poor care. Unless you do an autopsy and 100% determine the cause of death there's no use blaming yourself.
Even the best of sororities will have some level of stress present because you are housing a group of aggressive and territorial fish together in close proximity. As most fishkeepers know stress can lead to disease or parasites taking advantage of particularly compromised fish. I think this is one of the main reasons why sororities do seem much more prone to sudden outbreaks of disease than other forms of 'community' tanks.
If you have some valuable or particularly prized females it may be better to house them individually as I think you do reduce the possibility of stress, disease and death by doing this.
Yeah... I have a few that were $30 each... and the others range from a few dollars to fifteen. Personally some of the ones that were cheaper I like best, better form and better personalities. I'm going to keep watch on them. But I just feel like it's happening too much. Though Danica was the shy one and seldom came to strut her stuff to me during feedings and Ini ALWAYS showed her stress stripes, no matter what I did. Secluded her, or in the sorority she was always stressed out.
i would check around your fish tank. it could of jumped out.i have a 5 gallon qt tank.i put a pair of guppies in and in the morning the male was all dried up,he jumped out of the smallest and only opening by the filter. so yours could of jumped out
I realize this is an older thread, but I am now experiencing something similar... It seems to happen to the younger/smaller fish when I add them... But my girls are sneaky, they don't eat each other when I'm around and watching... I think they know when I leave, or the lights are off... and I come back to check, and ... where's your new little sister??!!
I have read about people who claim, "I have a male in with all my females, and they're fine" but they are typically told that when someone in the tank decides they're gonna do away with one of the fish, it happens FAST. And I think there's a difference between the change-up-in-dominance, when they flare and nip and curl up sideways at one another, to establish pecking order among the females.
Last time I actually upgraded to a new tank, I threw minnows in the tank -- call me crazy, but I wasn't willing to risk my "family" of betta girls; I figured if the feeder fish lived, the cycle was over... After I added the betta girls, I woke one morning to find a small minnow (partially) hanging out of my largest betta girl's mouth... So, I have this idea in my head that a sort of frenzy is possible if they decide they're gonna get rid of someone in the tank.
My current setup... Everyone* healthy and happy!
2.5 Gal: Mr. Limpet (1 male Betta) + snail, live plants - Betta Bulbs gone WILD -- he loves to curl up in them...
10 Gal, split divider: Mr. Poirot & Mr. Ballou (2 male bettas w/ black divider) + mystery snail, live plants - Betta Bulbs, Pothos, and water plants I can't pronounce...
29 Gal Sorority/Community: 10 Female Bettas (*1 is missing??!!), 3 minnows, 4 mystery snails, live plants - LOTS of Pothos, 1 mint, and water plants I can't pronounce...