i just looked in my tank and discovered that my bettas tail is split completely in half, almost to her body! When I looked an hour ago, I didn't notice anything - no splitting at all.
What would cause this? I'd love to post a picture but I don't have my camera cord at the moment (or a smartphone). It is split horizontally. She is a crowntail.
10 gallon community tank, peaceful fish (cories, platies) so I really don't think nipping was the problem (but one of the platies is male and it's possible he nipped, but like I said I really don't think this was an aggression thing). Water is on the hard side, pH is 7.6-7.8, water parameters are normal (nitrates are a bit high lately, ~40ppm but ammonia and nitrites are 0). Live plants, 4in air stone, aquaclear 20 filter, gravel substrate.
I'm hoping an expert can tell me what might have caused this - if it had to be rough play (nipping, tail biting, caught on decor, etc), or if water conditions, stress, or something else "unseen" can cause this severe a split.
Also, what should I do about it? I just had her isolated for a week and a half to treat ich (with saltwater) so I don't want to isolate her again (but obviously will if necessary). Will it fix itself? I've never seen a split this severe.
Thanks! Please help!