Ive had these IT datnoids for a little over a month now, one of them is more dominant than the rest. I have 4 all about 2" in a 135g tank. The dominan one is the only stable one and the only one that swims around, the others just hide in the corner behind the heater and are always unstable. They eat perfectly fine but then swim right back to there corner before the dominant one can chase them back.. Is there any thing I can do to stop it from picking on the rest and make them swim around? Thanks