i have 4, is this a lethal idea? i have two that are so territorial over the other two. my two biggest are in perfect shape swimming around with eachother, the other two have severly nipped fins, a bite right behind the head on both, and very stressed. what do i do? add a boat load of guppies? through in a boat load of convict fry as like a dither fish. or do i need to part them out.