white tail and fin spots then they split

Question
QUESTION: Hi i have a 300litre tank with dicus, geen severums,sharks ,plecks.
I have two large filters .water quality is perfect nitate 0 etc
But the fish keep getting a sought of white on their tails and finds then they split both tail and fins
I have tried melafix industrial strength and primafix it go's then comes back
Do you have any ideas

Best Regards Mark

ANSWER: Hi Mark,
 It sounds like they are biting each other.  That is the most common reason for fin damage and
is much more likely than any sort of disease.

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


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

QUESTION: Sorry
Its not biting,there is a definite white patch all over fins
or tail before any splitting appears
Any other suggestions

Please

Regards Mark

Answer
Hi Mark,
 Actually those are exactly the signs of biting. You will see white patches long before you see splitting. It is the equivalent of scarring and bruising in humans. Fish can be bitten to death without any splitting of fins.

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