what happened?

Question
I have two goldfish, a black moor and a white comet in a fish tank for the past 2.5 months. Typically I leave them over the weekend unattained and I come back and they are fine. However, this weekend when I came back, I noticed that my smallest goldfish was biting on my black moor. The poor moor has a gnarled fin. I took the moor out ASAP, but now he just sits at the bottom of the bowl, not swimming. What happened to make my goldfish do that and will my moor recover. Please help, he is usually so active and lively.

Answer
Hi Sabrina,
 There doesn't have to be anything in particular which causes that. Fish will be aggressive from time to time.  As fish get older, then tend to get more aggressive in general.  
I cannot say for sure about your black moor. If the damage was just to the frilly part of the fins, then generally they will grow back. If the damage was deeper, then is is more serious. Make sure that your fish has clean water by doing a 25% water change once a week, every week. Clean water is the best thing to help him recover.

-- Ron C.
  rcoleman@cichlidresearch.com
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