Tiger Oscar acting strangely

Question
hello I am a proud owner of 2 full grown Tiger Oscars the oldest is about 4-5 yrs old and all of a sudden has been swimming vertically with head always facing the bottom of the tank,he seems to be acting otherwise normal,he will come to me when I approach the glass and is interactive with the other younger Oscar(2yrs old)he is also eating, this has been going on now for the past 5 days I, upon examination I actually see that he is slowly getting worse,however his colors,scales,gills and fins are all in excellent condition....DO YOU HAVE ANY IDEA WHAT THE HECK IS WRONG WITH HIM??   
THANK YOU FOR YOUR TIME PAUL....

Answer
Hi Paul,
 Hmm... that is hard to say.  First, do you have sand or gravel or something on the bottom of the tank, other than just the glass.  If there is nothing there, then the fish's reflection really bothers some fishes. Assuming that is not the problem, then it is hard to say. If he were listing to one side or the other, I would be more worried because that would indicate a swim bladder issue, possibly an infection. I guess, from your description, I am not sure that there is anything actually wrong with him.  Oscars do some strange things at times.

-- Ron Coleman
  rcoleman@cichlidresearch.com
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