Goldfish Velvet Disease: Causes, Signs & Treatment

Goldfish are a type of freshwater fish that can be found in many different parts of the world. They are popular pets and can be kept in aquariums or ponds.

Goldfish are known for their bright colors and for being able to tolerate a wide range of water conditions.

Goldfish velvet disease is a parasitic infection that affects the skin and gills of goldfish. The disease is caused by a tiny organism called Piscinoodinium, which attaches to the fish’s skin and gills and inhibits their ability to breathe.

The signs of goldfish velvet disease include lethargy, loss of appetite, clamped fins, and reddish-brown patches on the skin and gills.

Goldfish Velvet Disease

What is Velvet Disease

Velvet disease is a parasitic infection that affects your fish’s skin. This parasite attaches to your fish’s skin and produces a sticky substance that can smother your fish.

The algae also release toxins that can damage your fish’s skin and gills.

Piscinoodinium causes protozoal infection in fish called velvet disease. This parasite attaches itself to the gills and skin of the fish, where it begins to feed on the fish’s blood.

The parasite causes the skin and gills to turn a dark brown or black color, hence the name “velvet disease.”

What is Gold Fish Velvet Disease

Fish velvet disease, also known as Gold Dust Disease, Rust Disease, etc., is a common goldfish disease and deadly condition that affects goldfish and other members of the carp family.

The disease is caused by a parasitic dinoflagellate protozoan, resulting in the fish developing a velvety coating on their skin.

The protozoan multiplies rapidly in the bloodstream, clogging the fish’s capillaries and depriving them of oxygen.

As a result, the infected fish will become lethargic and eventually die. In addition, the affected fish may have difficulty swimming and breathing and may subsequently die.

Causes of Goldfish Velvet Disease

The causative agent of Goldfish velvet disease is a type of protozoan parasite called Piscinoodinium.

This protozoan attaches itself to the gills and skin of the goldfish, where it multiplies and causes problems. Several factors can contribute to the development of goldfish velvet disease.

Parasitic Infection

Velvet in goldfish is caused by a dinoflagellate parasite inside the tank water. This causes the scales and body to look rough and dusty.

This parasite reproduces and grows by photosynthesis and then looks for fish to provide itself with hosts.

Then, this parasite detaches from your fish’s slime coat and eats the cells of the slime coat, then repeats the process again. Velvet appears unexpectedly.

Poor Water Conditions

Poor quality water is a significant contributor to overcrowding and poor nutrition.

Poor water quality is one of the most common causes, as high levels of ammonia and nitrates can create an environment conducive to parasite growth.

Improper Diet

Nutritional deficiencies result from improper diet. A poor diet will make fish susceptible to disease.

Stress Condition

Stress can also make goldfish more susceptible to this disease. Velvet can be treated with medications available from pet stores, but it is crucial to address any underlying causes to prevent a recurrence. Fluctuations in water temperature can create stressful conditions.

Life Cycle of Velvet Parasites

The parasite is smaller in size and is almost invisible on gold-colored fish. Three significant phases are found in the single-celled parasite’s life cycle.

First, a parasite grows by dividing into as many as 256 tiny parasites called tomites.

Second, tomites use photosynthesis to produce and consume the fish’s cells.

The juvenile free-swimming stage called motile tomite swim in search of a fish host and became mature within three days after entering the fish’s body.

The adolescent tomite enters the slime coating of a host fish finally. Once matured, they detach from the fish’s body and become a single cell again.

Sign & Symptoms of Goldfish Velvet Disease

One of the most common symptoms of velvet disease is a greyish-white spot or colored film on the fish’s body. Other symptoms can include lethargy, loss of appetite, and respiratory distress.

-Early symptoms of the disease include skin irritation, flashing (when the host fish rubs its body against objects in the tank to relieve the offense), and labored breathing.

Rapid killing is a key symptom, excessive slime, and fins clamped against the body. Whitish or yellowish coloration is visible in the patches on the scales.

-As the infection progresses, the skin of sick fish may become covered in a velvety film, and they may lose their appetite and become lethargic.

-Fine yellow or rusty colored film is visible in advanced stages on the skin.

-In severe cases, the fish may stop swimming altogether and eventually die.

Prevention of Goldfish Velvet Disease

Fortunately, there are several steps you can take to prevent your goldfish from contracting velvet disease.

The most critical step in preventing velvet disease is maintaining good water quality. Ensure your aquarium is well-filtered and use a water heater to keep the water temperature at a consistent 68-72 degrees Fahrenheit.

-Increasing temperature will significantly shorten the time for the free-swimming phase to occur. Additionally, do not overcrowd your aquarium and make sure to clean it regularly.

-Water quality parameters like pH, ammonia, nitrite and nitrate levels, etc. should be measured by a water testing kit and monitored properly.

-You can also help protect your goldfish from velvet disease by giving them a healthy diet. Feed them a balanced diet that consists of both fresh and frozen foods and good quality flake food. Healthy fish can develop immune systems against velvet disease quickly.

Infected host sick fish are placed into the hospital tank. Maintaining good water quality and stock water exchange is an effective way of preventing velvet disease. Replacement of 50% aquarium water daily for 14 days will ensure proper water management.

Treatment of Goldfish Velvet Disease

There are several ways to treat goldfish velvet disease, including using anti-parasitic medications, raising the aquarium temperature, frequent water changes, and increasing the water flow.


Sick goldfish are separated immediately in other fish tanks to control disease outbreaks

Salt Bath

A salt bath is an ineffective cure for a goldfish with velvet disease. One tablespoon of aquarium salt per gallon of water effectively against gold fish velvet diseases and works very well with external parasites.

Sodium Chloride is used to mitigate reproduction, but this treatment is not enough for the complete eradication of an outbreak of disease. Excess salt needs to be removed by replacing 25% water.

Chemical Treatment

Velvet parasites derive energy from photosynthesis, so subjecting them to darkness for several days is beneficial to complement chemical treatments. Erythromycin may be administered to fish for secondary bacterial infection.

Malachite Green

Malachite green and Methylene blue are very effective on sensitive fish. Parasite Guard is also effective against external parasites.

Copper Sulfate

Anionic copper treatment, chelated copper, is compelling. Free-form copper is an effective treatment for velvet fever.

However, you need to use this treatment carefully because you can burn the fins of your goldfish if you give them too much copper.

So you have to check copper levels in your aquarium water tank.

Final Words

In conclusion, goldfish velvet disease is a severe and potentially deadly illness. It is essential to be aware of this disease’s signs and symptoms and take steps to prevent it from affecting your fish.

Early diagnosis and treatment are crucial to preventing the disease from progressing and potentially killing your fish. If you have any questions or concerns, please consult with a qualified aquarium specialist.