Parrot Fish acting funny

Question
My mom let her 50 gallon aquarium water get pretty dirty- my sister cleaned it really well, replacing the gravel even, and the water got really clear. Two of her big organge parrot fish got a little pale after the change, but one of them seemed to be darkening up again. Now, the one that never changed color has parked himself at the bottom, for several days, hiding in a rock structure. The other two are hovering around him. She's been feeding them little balls of frozen shrimp (as a "treat" to compensate for their stress). Is there a test we can do to make sure the water is OK? Anything that is best to feed them?  We have had this fish for several years and they've thrived. We really don't want to lose them!

Answer
Hi Michelle,
  There really isn't a "test" that is going to tell you anything important.  

  While I appreciate the desire to really give a tank a good cleaning, it isn't always the best thing to do because you can disrupt the chemistry of the tank.  More frequent smaller cleanings would be a much better way to go in the future.  25% water changes are ideal.  Sometimes when you do a really big "clean" you actually release a lot of stuff into the water that was previously more stable in the bottom of the tank.

  In the short term, consider doing a 25% water change today or tommorrow.  

-- Ron
  rcoleman@cichlidresearch.com
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