kribensis behavior

Question
I just got a male ( i think) kribensis about a week ago.  I added him to a tank with several catfish and large guarami.  The problem is, the kribensis started to chase after the large spotted catfish and has actually eaten off half of it's whiskers.  It also has been nipping at the fins of the catfish.  I don't know if the kribensis is just aggressive or if it is hungry.  I've been feeding it pellets and tropical flakes.  Does it need a different diet?  Please send helpful information as soon as possible.  Thank you!

Answer
Hi Shayla,
  That seems extraordinarily aggressive for a kribensis. Any chance you could send me a photo of the fish?  Please send it to the address below.  

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