My female Oscar has two almost identical small holes in her Pelvic Fins. Viewing her in the tank, you can see daylight coming through both Pelvic Fins almost in the same spot on each side. This in not at the edge of the fins either but almost right in the middle of each. The holes are about the size of a pin head and only visible when she flexes her fins open. It doesn't seem to be getting worse nor does it seem to be going away. I doubt this is fin rot because it is not at the edge of the fins.. But it could be? Ideas?

Had this happen before. In fact a couple of my juvenile Oscars have got slight frayed fins. As long as there is nothing that looks out of place, such as white substances around the hole etc etc, then just keep an eye on it and I'm sure it will heal up okay. I distinctly remember one of my Oscars having a hole in its Fin, looked like it had been shot. It soon disappeared.

No, I don't see any fungus or anything around the holes. I am only concerned because the holes may be a tad larger then when I first spotted them a week or so ago. If itgets worse instead of better, I may treat the tank with something. Salt perhaps or some other medication. The holes are so small that without being back lit you probably wouldn't see them. Also, those Pelvic fins are rarely flexed open all the way.

I just did a 55% water change. I do a partial water change weekly but occasionally do about 50-60% like today. I'm just amazed how much gunk I can pull out with a python water vac anyway. The tank bottom really gets alot of heavy chunk debris (poop and food).

I decided to treat the tank with a combination of aquarium salt and melafix. I'll dose the melafix all week. Better to be safe rather then sorry.

On the subject of filtration, this tank has more then sufficient filtration for a normal "community" type of set up but not with these Oscars. Plus a gravel vac is a sure necessity as those chunks and debris do not make it to the filter strainer, they just lay on the bottom and integrate with the substrate. Anyone not using a gravel vac such as a water python is going to have a "dirty" Oscar tank.