Hi! I have an albino cory with a missing fin. She (I think she's female anyway, always a crapshoot when they're small) is about three or four months old I think. Had them both since Nov.11 2020.
Tank was set up October 2020, so it's four/five months old thereabouts. 10 gallon tank w/ aquatech 10-20 gal
filter, tetra 2-10 gal
heater. Two albino corys (her and a male, same age, a little smaller. Picked them up together).
76 degree F (usually between 76-78; it's cold outside now)
(done by test strip except for ammonia which was w/ the water kit, so it isn't super precise)
Gravel vac was about two weeks ago, water change was maybe a week. Nothing new added to tank. Fed with a mixture of hikari sinking carnivore tablets, tetra tropical flakes, and rarely tetra dried bloodworms (which I don't think they like).
Photos attached below of injured (1st image) vs. uninjured side (2nd image)
Should I be concerned / should I do anything about it? I hadn't noticed until today but looking back in old photos, the first time I can see her without the fin is Jan. 19 2021. So far she's been swimming okay, but I had noticed one of my fish (hard to tell apart, considering they don't have markings) was swimming a little curved (like kept their tail to one side) maybe was when she lost it?
Thanks in advance for any help!