fading color on oscar cichlid

Question
QUESTION: I have an oscar cichlid that has been a very rich black and orange. Lately, he
appears to be fading to a lighter grey color.  He is eating vigorously, has no
aggressive tank mates, provided with a variety of fresh and freeze-dried foods,
and appears to be growing.  It looks as though there are 6 or 7 scales that are
missing. According to the aquarium store, the water is "fine". Should I worry?

ANSWER: Hi Maurey,
  Color changes are normal for cichlids such as oscar.  I would not
worry about that.

  The missing scales are something to be concerned about.  Is another fish biting him, or is possibly bashing against a sharp object in the tank?

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



---------- FOLLOW-UP ----------

QUESTION: after doing a partial water change, they restested the water and it was high in
nitrites. the aquarium store recommended i put a nitrosorb pouch into the
filter. after that, the water tested fine again.  oscar's scales have grown back
and the color is coming back.  he's the big man in the tank. the other fish are
smaller and not interesting in starting anything with him.  it appears that they
get along well.  do oscars shed scales so obviously when they grow?  what is
the reason they change colors?  does it indicate a fertility cycle?  oscar and i
have got a little bonding goin' on, so i'm attached.  he's learned to eat from
my hand and do some jumping tricks.  i really don't want to loose him
anytime soon.  i just rescued him four months ago.
thnx for responding so quickly.
maurey

Answer
Hi Maurey,
  Oscars change color to indicate mood to other fish, and they do this all the time.  

  Fish never shed scales to grow.  The only reason a scale comes off is if the fish bangs against something, has some sort of disease or most likely, if another fish bites it off.  Keep a close eye on things: size isn't everything with fish and a highly motivated smaller fish can do a lot of damage.

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