goldfish and colourful pet fish

Question
I had 7 fishes, 5 goldfish and 2 colorful fishes. They were getting on fine but one day the goldfishes killed both of colorful ones. Why's that?

Answer
Hi Abena,
  Like all fishes, goldfish can be territorial.  If there is only so much space in the tank, and the goldfish think that they need it all, then the other fish were killed to get rid of them.

-- Ron
  rcoleman@cichlidresearch.com
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