I had two oscars now only one. I lost my albino to I believe hith. I tried everything suggested here to help her live but unfortanatly she passed two days ago. I will include some pictures to help out. hopefully they are not to graphic as I took them after she past to show here gills.
she was about 5 inches while my other is almost 7" I picked them up at the same time when they were about 1 1/2". almost 6 months and they had grown so fast.
any ways hopefully by me taking some pictures it will help someone else avoid a loss of there fish. I had not seen any other pictures of what had happened to my oscar so am not sure if it is actually hith or not.
the first sign of gill damage


The two together


Pretty good friends


After she passed

She was sitting at the bottom of the tank with labored breathing before she passed that night. she had lost her appetite and I knew it wouldn't be long.

Damaged gill


good side


Inside bad gill


In conclusion the marking on her gill lasted about a month and it never really seemed to bother her at all. it took three days of her suffering with labored breathing it was so hard to keep her alive I felt so bad. May Suzy the oscar go to A better place. thank you for viewing this and please feel free to help me and other forum members help prevent this if possible.
thanks.

A photograph would be very helpful, we can't really help without one.

I was trying to figure out how to post and accidently submitted the topic. Pics are up now.
thanks.

I'm not really sure if that is hole in the head disease. I'm wondering if your fish had some kind of gill problem. Did you notice anything unusual with the gill filaments? Healthy gills should be a nice pinky red colour. Have you by any chance got a plec in your tank? What about your water conditions, have you tested for ammonia, nitrite, nitrates and pH. Is your tiger o okay? Check for any small holes. There are two suspicious looking areas behind the left eye, whether they are just markings I know not.

The problem with creatures with hardly or no colour pigmentation is it's not as easy to tell what's going on. Were the holes going right through to the gill filaments the last things to appear? In other words, did things start from the outside?

When she was alive both gills were a nice red fleshy color. I notice it starting from the outside as a small red spot on the left gill. after the hole had shown up through the flap the gills still looked good. It was a couple of days before she passed that I noticed inside of her left gill was turning kind of mushy? not like a healthy gill where you can see all the little teeth like things on the gill it all turned in to one big flesh piece? you can kind of see it in the picture taken in her mouth.
I do have a Pleco in the tank but they never bothered eachother he pretty much keeps to his own.
the pictures were taking about a day and a half after she had passed. I didn't have time to take a look at her when I pulled her out of the tank that morning. So the all the normal looking part of the gills had lost there color due the time she was sitting in a baggie with water.

The reason I ask about the plec is they have been known to attach themselves to fish when they sleep, and when this happens they can cause ulcers. However, since this started off as a red dot, I don't think this is the case. It's really difficult to say. If that was just the wound with no hole going through to the gills, then I would say it wouldn't be fatal, it would be perfectly treatable. Ulcers can start from the inside work themselves to the surface, sometimes you can't see anything at the surface. I couldn't say whether this has happened or not. It's more than likely a problem with the gills, maybe an infection developed, I'll be honest with you, I couldn't say for sure. Did both gill filaments do the same thing, or was it just the side of the hole?

just the one side. Maybe it is a birth defect I guess I will never know. I had searched the internet for ever trying to find something like this and there was absoluty nothing like this on any other fish. all my other fish in the tank are doing great looking good and acting like they should. anyways maybe some other people will jump in and maybe help out on diagnosing this weird hole in the gill.
thank you for your time.
I will post some other pictures of my other fish.

There are very few experts on fish. Fish are one of the hardest features to diagnose and treat. The only sure way of finding out what was wrong with your fish is to carry out the post-mortem. This would obviously distinguish whether the gills were diseased, whether that be fungal or bacteria. The problem is, once you've got a wound, infection can set in very easily. So if indeed this was: the head disease which penetrated the gill plates, disease could have set him quite easily. Like I said before if it was just a small wound without the holes, I don't think that would have been fatal, the fact that you've got a hole going right through to the internal organs is 100 times worse.

By the way, I hope you know what you've let yourself in for with tinfoil barbs.

sorry for the loss.
just a piece of experience with one of my client.
he had an oscar pair, about 8" long together with a
a 10 inches long plec. one night, he heard water splashing
in the tank but give no attention at all. the following
morning, one of his oscar is dead. we tried to figure out
what happened that night and how in hell it got that
hole at the side abdomen. he observed and two days later,
there was another splashing in the tank. when he checked,
he found out that the plec is trying to anchor its mouth
at the remaining oscar. from there, we figure out that the
hole at the abdomen was caused by the sucking of the plec.
the damage is similar to what you had with your dead o.
hungry plec will try to grab even a bigger fish. once the
mouth got taste of that slimy substance of the fish, it will
never stop until done.

i believe you've got plec problem over there.