spots sreading over mature oscar

Question
I have a mature oscar, and yesterday i noticed several spots on him. The spots look like the scales are missing, brown and orance coloration gone in these spots, and the spots are white. they kinda look like scratches, and you can see parts of scales hanging on. They are only on the one side of the fish. On his tail, and upper back, in a line. I changed 60% of the water in the aquarium, and scrubbed up his tank real good. Ph is at 7.0, water temp is 78 degrees. what are these spots? how can I get rid of them, and make my oscar healthy? What could be causing it? He has sea shells in his tank that he loves to play with, moveing them around in his mouth, and sometimes smacking them with his tail. Could that cause this? He seems to not be bothered by the spots, but they are spreading, they dont look deep, just like color was stripped away. what can i do to clear upthis problem?


Answer
Hi Brandon,
 I assume that there are no other fish in the tank?  Otherwise I would say that he is being attacked by another fish.  He might be scratching himself on the shells.  
 Be sure to change 25% of the water EVERY week in an oscar tank.  That is much better than doing less frequent larger water changes.

-- Ron
  rcoleman@cichlidresearch.com
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