We can observe a whitish to milky turbid skin, due to excess slime (mucus) secretion that is generally caused by parasite-related skin irritation. (Ill. 52+53+54+55+56)
This skin irritation may also be caused by poor water quality and bacterial or viral infection. (Ill. 46-48, 51+57+58)
Turbidity of the skin caused by parasites could after a few days develop into a red bleeding skin (see below), caused by a secondary bacterial infection on the damaged skin.
This usually involves mass mortality. (Ill. 55 + Ill. 76 see p. 33)
With Angelfish aids and Discus disease (see Chapter 6. Fish Diseases) the fish exhibit excess slime on the skin. (Ill. 49+50)
Tip: Turbidity of the skin should not be confused with something that looks like a ?fine powdery film? for which reference will be made to ?Spots/dots/wart-like clumps? (see p.36) (e.g., Ill. 91).