New to this in last few weeks, but have a 55 gal tank with 2 gouramis and 2 angels. The angels have been acting strange and sitting at bottom of tank not seeming to eat. Show no visible signs of being sick except that. 1 angel died 2 days ago, no the 1 remaining is still doing that - just sitting at bottom of tank.Before this the 2 of them were swimming around alot. I'm not sure but this don't seem normal behavior. Has anyone had this problem before and can I do to stop the other angel from dieing on me?