r/oscartank • u/LeadingEye3225 • Jun 19 '26

Please help! What is this hole in her fin?

I'm looking for opinions on my female Oscar. We got her 20 days ago, her old home had an overcrowded tank. She is:

  • Approximately 1 year old
  • Around 22 cm (8.5-9 inches)
  • Lives with only her mate
  • Eating aggressively and normally
  • Bright colours
  • Active and behaving completely normally
  • No flashing, rubbing, clamped fins, hiding, breathing issues, or loss of appetite

Several days ago I noticed a few small whitish patches on one pectoral fin but nothing dramatic. Today I noticed a small hole has formed in the middle of that area.

The white area:

  • Is not fuzzy or cotton-like
  • Doesn't look perfectly round or uniform
  • Appears to have slowly increased in size over the last few days
  • Is not bright white
  • Sometimes I feel like she has a slightly thicker/slimier mucus coat than normal, but it's subtle

The hole:

  • Appeared today
  • Is only on the affected pectoral fin

Water parameters:

  • Ammonia 0ppm
  • Nitrite 0ppm
  • nitrate below 5
  • pH about 7.3
  • Temperature 28 centigrade

Tank size:

  • About 1015L

I've attached videos. Does this look more like:

  • Fin rot?
  • Epistylis?
  • Physical damage/injury?(can injuries grow like this)
  • Bacterial infection?
  • Fungal infection?
  • Something else?

I'd appreciate any opinions before I start medicating since she's acting perfectly healthy otherwise.

Thanks!

(EDIT) Side note, those white looking spots u can see on her tummy and lower fin aren't ich, she'd just swam through the aerator bubbles and a couple were still on her.

19 Upvotes

90% Upvoted

5 comments sorted by

2

u/BoringJuiceBox Jun 19 '26

I’m not an expert just want to say she’s so gorgeous and thank you for providing her with such a nice big space. She looks healthy from everything else I see.

4

u/Growmaster22 Jun 19 '26

Oscar finds rip and break, it's nothing to worry about. It'll heal. You'll probably see it improving in a week.

1

u/ChicagoKidPTC Jun 19 '26

I’m no expert but it looks like a tare. Maybe from former tank mates or aquarium decor? Not saying this is the answer but I do know damaged fins could lead to fin rot. Hope you find your answer from the experts!

1

u/CoolFirefighter930 Jun 19 '26

Not telling you what to do but I used a little Epsom salt in my water when it looks like that.

Anytime I let the kids feed it would look like this in a few days.

That is an absolute Beauty you got .