Common Name: Velvet
Pathogen/Cause: Oodinium limneticum, Oodinium limneticum (FW) , Oodinium ocellatum (Marine counterpart)
Physical Signs: Powder-like white, grey or gold dusting on surface of fish (finer than ich, more similiar to the consistency of talc).
Behavioral Signs: Scratching against objects (skin irritation), clamped fins.
Potential Treatment: Aquarium Pharmaceuticals General Cure, Jungle Velvet Guard, also, many of the same cures for ich and other parasitic diseases will work.
Other Notes: Same warnings for treatment as with ich.
http://badmanstropicalfish.com/fish_pal ... tml#Velvet
There is a bunch of other stuff in the link with pictures.