7 yr old Oscar very sick

Question
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Followup To
Question -
I have an Oscar who seems to be quite sick. We've had him about 7 yrs now, maybe a little longer.  About a week ago I noticed a large spot on his left side, toward the front a little ways back from and a little higher up than his eye...kind of the side of his head I guess. It looked like he had maybe banged against a rock in the tank and lost 2 of his scales, leaving a fleshy pink looking indentation.  He also had ragged looking fins with little white spots on them.  I went to the pet store and got some antibiotics that were supposed to treat fin rot, fungus, parasites, etc. A broad spectrum antibiotic.  Followed instructions exactly but does not seem to have helped. The place on the side of his head at first seemed to get bigger but now looks like it may be healing. Can't tell for sure but part of the fleshy pink area is now turning gray like the rest of that part of him.  Now he just seems to want to rest at the bottom of the tank. Not himself at all. Very lethargic.  Upon closer inspection it appears that when he breathes he is only using the gills on one side (oddly enough, the side he has the injured spot or whatever it is).  The gills on the other side do not move at all when he breathes. In fact, I havent seen him move his gills on the side opposite the spot in more than 48 hours.  
He has always been relatively healthy until now. The few times he has been sick I have always been able to identify and succesfully treat the problem. This time I have no idea!! Please Help!
He is in a 65 gallon tank with 2 algea eaters and a small koi.  What is the typical life span of an oscar? Could it be he is just getting old or is there some type of illness here? Any advice is GREATLY appreciated...we've had him so long he's become a part of the family.
Answer -
Hi R,
 That is really difficult to say.  It is possiblle that he is getting old, though, oscars have been known to live substantially longer than 7 years (well into their teens) but you probably don't know how old he was when you got him.  So, it might be old age.

 In any case, the most important thing for oscars is good clean water.  I assume that you do regular weekly water changes (of about 20-25%).  If not, you should start now.  This will do more for him than any amount of antibiotics and chemicals. The problem with those is that the very broad-spectrum ones do a lot of damage as well as good and the very specific ones treat only really specific things, so unless you know exactly what you are treating, I am very reluctant to use them.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>
I do regular water changes. I am assuming the oscar was very young when we got him because he was VERY small at that time. He is now HUGE, close to 10 inches in length and more than 3" wide...bigger than any others I've seen. But based on his size when we got him, I don;t think he is more than 8 yrs old so if they typically live into their teens then prob not old age.  I just checked on him again and he is swimming around more. Also using both gills when breathing.  He is still eating so I'm not too concerned yet.  Is it possible that the spot he has is actually hole in the head? Whenever he has had that in the past it has always been right in the center on the top of his head and we've always caught it early and treated successfully with virtually no scarring.  Didn't think it could be that this time due to location being more on the side of the head than on the top but dont know for sure. When I looked at him just now I noticed what looks like another small spot identical to the larger one that was not there before.  Just a small circle, not quite the size of a pencil eraser, but same fleshy pink color as the other spot and indented maybe 1/4".  Looks like a small hole.  Should I treat with something specific to hole in head?  He doesn't seem to be terribly stressed. His fins are not clamped and as I said before, he will still eat, even chases live food around the tank still.  Only symptom other than the spots and ragged fins (which could just be from other fish biting or him bumping stuff in the tank)is brief periods where he sits at bottom of tank, which is not terribly unusual except that he would usually swim around when I came close to the tank before and now still just sits there during these times. Maybe he was just sleeping, not sure but the holes are really starting to worry me. Thanks.

Answer
Hi,
 It could be signs of hole in the head (it's pretty hard to tell from here).  If it is hole in the head that means you need to change more water, or better yet, more frequently.  The medicines that supposedly treat hole in the head actually just treat the bacteria associated with hole in the head -- increasingly we are believing that those bacteria are a secondary infection and not the cause of the disease in the first place.  The trouble with oscars is that they are messy eaters and very sensitive to stuff in the water, particularly disolved nitrogen based stuff, such as bits of food, waste etc.  
 10 inches is a good size but he could get half as large again as that. Give him lots of clean water regularly and I suspect he will perk up.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>