Ulcer?

[cool_jool]

Hi

I have had my small tank for just over a year now. I have had a stable population for a number of months. One of my danios has a 3mm hole? in his side. I had noticed what looked like a scrape after the last water change, but that seemed to be healing. The 'hole' is underneath the scrape and does not appear to be connected. I have noticed it being chased by the other two danios and so have isolated it. Could I have damaged my fish? It does not look like there is any fungus, no white fur. The water levels are all clear. Please help I have never seen anything like it and would hate to think I have hurt my fish.

Thanks Cool_jool

 

[Delirium]

I had an oscar that had "ulcers" not all that long ago.
I treated the water with Melafix, and it cleared them up in about 2 weeks.
Haven't had a problem since!
Melafix is wonderful!