aggressive tank

Question
I just move my fish from a 50gal to a 120 gal tank I also added a couple new fish in the process. This tank has turned so aggressive I have to keep the light off to have peace in there. They like to gang up on one fish at a time till they have it cowering in a corner. How can I stop this? please educate me with what is going on and what to do.  Kindest Regards... Laura  p.s I have 12 fish in the tank right now.

Answer
Hi Laura,
 The key to peace in such a tank is structure.  Structure can be rock, wood and/or plants (real or plastic) but you need a LOT of it.  A oouple of rocks won't do it.  I consider a tank to have lots of structure when I cannot see the back of the tank when looking from the front.  If you have lots of structure, the fish cannot gang up on a weaker fish and the weaker fish always have a place to hide (this is how fish survive in the wild).

-- Ron
  rcoleman@cichlidresearch.com
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