oscar problem?

Question
no other fish accept for a pleco,they actually get along quite nicely.Also it eats fine has a big appitiete, moves normal, is very active.. It seems fine but i hear that they can seem fine for a while before serious signs occur.Thank you so much for your help btw :)
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no worms to my knowledge at all. I do regular water changes. quality seems fine. I figured a better way to describe it. If you've ever accidently burned or microwaved Styrofoam (jeez did i murder that word?)the holes it leaves looks like that. like its been eaten away.the hole actually looks like Styrofoam.
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I have had a tiger oscar for about 6 months now, but very recently i notice a small hole on the side of his gills but more up towards its mouth. The hole does not look like pictures ive seen of hole in the head. It looks more like it was eaten away by acid (best way i can describe it). It does not bleed or look to be raw, I just noticed it hasnt always been there.
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Hi Alex,
It sounds like your Oscar has external parasites that are attaching themselves to his body. Have you noticed any worms in the tank? Do a water change and tell me if you see any worms.

Regards,
Chloe.
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Hi Alex,
Are there any other fish in the tank with him? Is he being bullied by other tankmates? Seeing as Oscar's are very agressive and territorial they may have eaten some of his flesh. What other fish are in there?

Regards,
Chloe.

Answer
Hi,
If no other fish besides a pleco are in there then he has a bacterial infection. Use a medication called Penicillin at 10,000 units per liter. Treat with a second dose in two days. Or use chloromycetin, 10 to 20 mg per liter, with a second dose in two days. This is a very effective treatment.

Regards,
Chloe.