10.2.3. Velvet

“Velvet” (Piscinoodinium pillulare, or “oodinium”, a dinoflagellate algae) is a very small parasite that looks like tiny spots of yellowish to golden-brown or rusty-colored varnish on the fish.

Well intentioned but ill-informed commentators on the social media are constantly identifying patches of white on fish as “velvet”. They are simply wrong. “Velvet” has a distinctive gold pigmentation. “VELVET” HAS TO BE GOLD COLORED. If there is a patch of white it will most often be bacterial (typically but not always columnaris bacteria). A patch on the forehead of a fish can also be tetrahymena. Hundreds of very small white dots can be chilodonella, costia, epistylis or tetrahymena. If the patchiness or spots are white it will NEVER be true “velvet”.

Note that many well intentioned but ill-informed commentators on betta forums are constantly saying that a betta with a frayed tail and/or gray patches on its body has “graphite disease” and that “graphite disease” is a type of oodinium. This is not true. “Graphite disease” is either a type of mycobacterium (“Fish TB”) or a bacterial disease like columnaris. And true “graphite disease” (an unusual mycobacterium) ONLY occurs in blue or blue black bettas. More about this disease can be found at this link:

10.16. Graphite Disease in Blue Bettas

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The disease is very similar to ich in how it progresses, with three stages; an infectious stage on the fish, a stage which falls to the floor of the aquarium and multiplies, and a small free swimming stage which attaches to the fish.  Like ich, it affects the gills initially and can thus be difficult to diagnose in its early stages.

Treating Velvet

Treating velvet is actually very easy. The treatments is identical to that used for ich. 

• Add lots of additional biofiltration (under-gravel, canister or sump) to filter out and thus kill the free swimming organisms. This added biofiltration also reduces the bacterial loading in the water which in turn allows the fish to devote more immune system resources to the pathogen.
• Add a Copper based medication (Cupramine, Copper Power, Copper Aide or Copper Safe) to the water of the aquarium to kill the free swimming organisms.
• Do not put the fish in a hospital/quarantine tank
• Do not change out or clean the filter media.
• Do not raise the temperature of the tank
• Add a 24/7 UV sterilizer to kill the free swimming organisms and reduce the bacterial loading in the water which in turn allows the fish to devote more immune system resources to the pathogen.
• Added aeration always is helpful

This disease is very rare in tropical freshwater aquariums. Over many years and literally thousands of diseased fishes I’ve seen on social media and fish forums, I have seen only a single case of velvet (the peacock below).

Using Copper to Treat Velvet

Some of the commercial copper medications which work include Seachem Cupramine, Copper Power, Copper Aide or Copper Safe. If one can’t get these medications one can get copper sulfate as “blue vitriol” in the drain cleaner section of the hardware store.

Copper has what is called limited selectivity. Copper medication kills invertebrates (ich, costia, velvet, etc.), it has much less of an effect on fish. It is recommended not to use copper in any aquarium which has shrimp, snails, or crayfish. Tanks with these creatures in them should be treated with a complete blackout for several weeks and adding some salt to the water. Salt (sodium chloride) is reasonably effective at a dosage of  one cup of salt per ten gallons of water (5,000 ppm).

To calculate the amount of copper to use technically one needs to know the “total alkalinity” of the water. This includes the amount of carbonate AND hydroxide in a given water supply. This is not easily done. So one has to approximate “total alkalinity” by using “alkalinity” or KH, carbonate hardness. Or one can simply follow the directions on the medication container.

Copper sulfate, CuSO4, treats most protozoan parasites on fish at a rate calculated by dividing the water’s alkalinity (KH) by 100 and using that concentration in ppm for the copper sulfate treatment. If the alkalinity is measured by dKH (typically a number between 1 and 20) the alkalinity needs to be multiplied by 18 before doing the calculation.

For example, aquarium water with a total KH alkalinity of 80 ppm (dKH of 4.4 or 80/18) would need 0.8 ppm (80/100 x 1 ppm) copper sulfate (CuSO4). If the KH (alkalinity) is over 250 ppm (14 dKH), do not use more than 2.5 ppm of copper sulfate. It is typically not recommended to use ANY amount of copper when the water is below 70 KH, or 3 dKH or lower.

This is a very small amount of copper sulfate. In a 100-gallon aquarium one part per million (1 ppm) is 0.38 grams. A typical 100-gallon aquarium with an alkalinity of 80 ppm or a GH of 80 (4.4 dGH) would only need 0.3 grams (0.38 x 0.8 = 0.3 grams) of copper sulfate. A twenty gallon would need only 0.06 grams.

It is important to keep up the therapeutic level of the copper for a considerable length of time. All signs of velvet should be gone for at least a week before stopping treatment. Many suppliers make cheap test kits for copper. Use them.

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