aggressive jewel cichlid

Question
Hi Ron,

I spoke to you recently about my fish, you may or may not remember. I have a jewel cichlid (kingsley) in a 20 gallon tank. The tank is heavily scaped with driftwood and fake plants (decided to go with fake ones so that they don't eat them). This weekend i went out and decided to buy him some new freinds as he seemed quite lonely. Unfortunately he isn't as welcoming as i'd hoped he'd be. I now have a benga cichlid, an angora cichlid and a sailfin pleco. He leaves the pleco alone but tends to bully both the cichlids. As a result the benga gets frustrated and attacks the angora too.

I spoke with the owner of the store I bought them at. She told me to put the jewel in "time out" in a seperate container to teach him that such behavior is unnacceptable, increasing the length of time outs as his aggression continues. During these timeouts the benga stops picking on the angora so I know that the jewel is fueling this cycle. I also read online that lowering the temperature will make him less aggressive, I just did that but have yet to put him back in the tank so I've not been able to see if this works yet.

Are there any other methods to decrease aggression in the tank? There are plenty of places to hide but he is such a bully that he'll chase them anywhere they go. I really don't want to come home one night and find a severed fish corpse.

Answer
Hi Matthew,
  The only way to reduce aggression (short of doing the time-out and/or actually removing a fish) is to add more structure.  I can't tell exactly how much structure you have -- one person's "Lots" is another person's "little". There is a difference between hiding places and lots of structure.  A hiding place is a place where a fish can go if it is in trouble.  Lots of structure means that one fish literally cannot see another fish in the tank, if they are in different "sections" of the tank, i.e., areas divided by structure.  

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