Though I usually personally attend to my bettas, I had my sister feed them for me this morning, as I left early for school. I didn't get home until late and noticed right away as I went to do their night feeding that Dovah's fins were rather spiky and discolored looking, enough that I was alarmed.
It doesn't appear to be normal tearing or shredding, like getting caught in a filter or other sharp surfaces (I have none in the tank anyway, and no problems ever with my gentle filter), so I'm a bit baffled as to what the cause is.
I'm not extremely familiar with fin rot as a disease, as neither of my two male bettas have ever had it, but I'm fairly certain it doesn't show up this quickly and severely in a 24 hour period. My sister isn't familiar enough with my fish to have noticed if he was like this this morning, so it could have been even less than that.
Dovah's sole tankmate is a ghost shrimp that I've had for a little over a month with no problems between the two, and I see this as the only other explanation for the damage.
Are either of these two the possible answer? I would hate to assume fin rot and medicate without needing to.
(sorry, I'm unable to test my water for now, and I need an answer ASAP!)
I do regular half water changes, and I'm sure there's nothing wrong with the water itself, as he has been perfect until tonight.
as you can see, his fins are usually rounded, not spiky. It's as though they worked in from the edges, which is the only reason I'm considering rot. (ignore the snail, he was removed after being eaten by said betta haha)