Sick Oscar turning colors

Question
About a week ago, one of my pacu fish died after his body and eyes slowly turned white. Now, i've noticed that my red oscar in the same tank has lost the red color and its been replaced with a yellow-mustard-green color. I can't tell whether he's actually turned this color or if something is on him. I just did a 50% water change. Is there anything else I can do? I don't want to lose another fish.  

Answer
Hi Julie,
 Are there other fish in the tank, perhaps one that might have attacked these two fish?

 Also, you should be doing regular water changes. I recommend changing 25% of the water in the tank once a week, EVERY week to keep fish healthy.

-- Ron
  rcoleman@cichlidresearch.com
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