Okay, I have a "10 inch silver arowana partnered with "11 A.gar and both are eating very well, but as I observed the aquarium, the bottom has some scales of the arowana, so I was wondering if they're shedding their skins off or it's some sort of sickness?.The arrowana has a bruise on his head(maybe bitten of by the a.gar) but I just wanted to be sure.