HELP my african cichlids look like they have have soot on them like black dust

I recently set up a new 75 gallon african cichlid tank an a few of my africans look drity alomost like soot on them..like black dust..tested my water and every thing is ok..one of my Chinese alage eaters died and i wiped it with a paper towel and i actuly got black off of it..has any one came access this before

Sent from my DROID RAZR using MonsterAquariaNetwork App
 
Top