Preliminary note: The spots may expand or develop into patches? and therefore sometimes also appear as whitish patches on the skin. Whitespot (Ichthyophthirius, commonly referred to as ?ICH?) or Velvet Disease (Piscinoodinium) look different (Ill. 91-95): - depending on the substrate (the fish species and its skin colour) - and depending on the degree of infection. There are also infections caused by a virus (Lymphocystis) or Sporozoa with symptoms that are not easily recognisable in the initial stages. (Ill. 96, 98, 99) The skin or muscles sometimes contain white or black nodules usually caused by parasitising worms. (Ill. 102, 103 and 105) Brackish water fish have been found to display white spots caused by another parasite, Amphileptus (Ill. 104). Mollies (especially sailfin mollies) with white spot caused by parasitic Copepods (Ill. 101) have been observed recently. Viral infections (due to the Herpes virus) may cause pockmarked spots (patches) on Koi. (Ill. 106) Tip: A whitish spot on a fish is not always a Whitespot or Ichthyophthirius infection.