Velvet
Oodinium pillularis
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Description:
Oodinium is a flagellate parasite that reproduces via cysts. Like ich, they burrow underneath a fish's skin. They start off as very tiny white specks on the fish. In advanced cases, the cysts cause the fish to be dusted with a yellowish-brown "velvety" coating, giving the disease its nickname of velvet. It is highly contageous. The fish may dart around and try to rub against objects in its tank and breathe rapidly. It is very important to note that just because the fish no longer have spots that you may assume they are all dead. They will continue to live in the water and surrounding tank after they have fallen off the fish. You must continue treating the tank for one full week in order to kill ALL the parasites (if tank kept warm; longer if not; see treatment below). The parasites on the fish cannot be treated; they can only be treated after they have fallen off and are in their free-swimming form. This is why the appropriate amount of heat is important. It would take weeks for the life cycle to complete at low temperatures!
Treatment:
Raising the water temperature will help to speed up the life cycle of the parasites (upper 70's to 80 if your fish can handle this). Salt baths are effective in getting the parasites off the fish. Products containing copper salt are very effective (note that this will kill snails) such as Coppersafe or Aquarisol. A number of other products can be found in stores specifically designed for Ich, but remember that the harsher the chemical is, the more stress it will cause to the fish too, not just the parasite.
Malachite green is not suggested for scaleless fish like catfish or loaches, or some other fish such as tetras. Products such as Clear Ich by Aquatronics are designed for these fish.
Prevention:
Quarantine new fish and plants. Do not cause any drastic changes in temperature in your tank. Always float new fish in their new tank for at least 15 minutes to allow the temperature to stabalize and match before releasing them in a new tank (but remember if you float in a bag to open it, as the fish need air to breathe).
