2 weeks ago i decided to repopulate my 75 gallon tank. For the past 2 years I have only had 2 Plackos in it, which have grown to about 6 inches each. I picked up 2 Oscars, a Jack Dempsey, a Green Terror and 2 orange colored Pikes. They were all juviniles, about 2-2 1/2 inches long. However, the Green terror was a little bigger. My Oscars and my Jack Dempsey are hiding behind the backgound from him. He keeps attacking them. They only come out to eat. I was told that these fish could defend themselves against eachother. But the only ones that aren't being bullied are the pikes. What can I do about this?