Betta Velvet Disease: Symptoms & Treatments

betta velvet disease treatment
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What do you do when you’re sick? I’m sure your initial reaction would be to Google every symptom, then you’d go see a doctor and then take medication, right?

Well, just like every other living creature, fishes can get sick too! And like humans, they also need care and treatment to recover.

Today, one such sickness we’ll be looking into is the velvet disease in Betta fish.

What is the Velvet Disease?

Otherwise also known as Coral, Gold Dust, or Rust disease, the Velvet disease is a contagious parasitic infection that attacks the skin or gills of your fish.

Velvet thrives on a stressed host by tethering itself to the gills or fin tissues and proceeds to kill the cells and absorb the nutrients from the fish.

As you may know, nutrients in a living thing are imperative, so if left untreated, the Velvet disease can result in death.

However, fret not, this guide is here to help you understand all things Velvet disease.

How Is Velvet Caused?

The Velvet disease is caused by a parasite called Oödinium, which is also categorised as algae as it contains chlorophyll.

Oödinium has a three-stage life cycle of Tomont, Juvenile, and finally, Adolescent.


At this first stage, the parasite starts to reproduce through cell division.

As each cell can divide up to 256 Oödinium tomites, the algae grow very quickly.


At this next stage, each organism continues to develop and will then be able to move.


At this final stage, the adolescent parasites will tether themselves to a host, which in this case, could be your Betta fish.

How they achieve this is by breaking through the fish’s slime coat, which is a protective layer that allows fish to swim and to keep bacterial micro-organisms at bay.

Once the parasite has entered the slime coat, it would start to kill the cells and absorb nutrients from the fish.

How this parasite enters and/or lives in your tank is usually through the following:

  • New unquarantined fish (as they may already be bearing Oödinium)
  • New plants (especially those not disinfected)
  • Old water (the older the water, the more time there would be for the parasite to breed and spread)
  • Drastic fluctuations in water temperature (could cause a sudden increase in Oödinium reproduction)


In addition to these elements, if your Betta is exhausted, unhappy, or anxious, they are more prone to get Velvet as their immune system would be weak.

Velvet Disease Symptoms 

It is imperative as a Betta owner to know what to look out for so that you can keep your pet healthy, and yourself happy.

Luckily, Velvet symptoms are visible, so it is important for you to observe and detect the disease on the onset and treat it before it advances.

Early Stages

One of the first few symptoms to look out for is behavioural changes such as eating lesser than usual, lethargy, or the fish’s gills moving rapidly as a result of breathing difficulties.

These symptoms are due to the parasites’ consumption of the fish’s nutrients, which causes a  loss of appetite and become weaker (thus poor eating and respiration).

Hence, when this happens, you will notice that they may not be swimming around the aquarium as much either, due to the lack of energy.

As the disease progresses, the skin would become more aggravated, and so, another behaviour you may notice is your fish scratching itself against objects in your tank or twitching.

The reason the fish does this is to seek relief or to try and get rid of the parasites on its body that irritates its skin.

betta fish with velvet

As aforementioned, one of the other names of the Velvet disease is Gold Dust or Rust disease.

How it gets this name is because another more prominent symptom of Velvet is your fish losing its colour with rust-like spots in replacement.

While it is not the disease itself that directly causes this ‘Gold Dust’ or ‘Rust’, it is caused by the fish secreting excess mucus to try and fight the parasite.

As this coating is dust-like, it would be easier to inspect by shining a flashlight at your fish in a dark room.

Advanced Stages

Although it is not impossible, it is a lot harder to treat Velvet in your pet in the advanced stages. Thus, if you notice any of these symptoms, do take immediate action by either consulting an experienced Betta keeper or a veterinarian.

Symptoms to look out for include:

  • Cloudy eyes (caused when there is a lot of bacteria in your tank)
  • Protruding eyes (due to fluid leak in the area behind the eyes which subsequently causes the eyes to pop out)
  • Clamped fins
  • Ulcers in the skin (caused by the parasite eating more into the Betta), and in some extreme cases,
  • Skin peeling (due to the fish’s constant rubbing against objects)


*Do note; symptoms such as the fish scratching itself, cloudy eyes, protruding eyes, and skin detaching from the fins, are also common in a lot of other diseases. However, if you notice these symptoms in combination with the others mentioned, then it is Velvet.

Velvet Treatment Options

Treating Velvet disease can be done by three simple steps first.

  • 80% Water Change

This first step would help to cleanse out the Oödinium in their tomont and juvenile stages.

This helps to prevent them from infecting your Betta fish, as well as to get rid of other pollutants in your tank that decrease your fish’s ability to concur Velvet.

  • Increasing Water Temperature to About 29.4°C

This increment in temperature should be done gradually over 24 hours, as a sudden increase could risk shocking your Betta and killing it.

The reason for this temperature increment is to lower the parasite’s lifespan as it is sensitive to temperature (the warmer the water, the more likely you are to eliminate oödinium).

If you keep your fish in a small tank of 15ℓ or less, it would be better, if possible, to move them to a larger tank of 20ℓ and above.

This is because a fixed temperature is needed to treat Velvet disease, and smaller bodies of water tend to have more fluctuations in temperatures than larger ones.

Not to mention, if you also choose to have a ‘hospital’ tank for the duration of treatment, it is also wise to treat both aquariums so that they would be free of the parasites.

  • Dim Lights/Placing Tank in the Dark for Seven Days

As mentioned earlier, Velvet is a type of algae due to its composition consisting of chlorophyll that photosynthesises, which in other words means that it requires light to survive.

Hence, reducing light or better yet, placing your tank in complete darkness for a week would starve the parasites in the water in their juvenile stages.


In addition to the above three steps, it is also good to add aquarium salt to the tank as it encourages slime secretion in your fish, which as established before, helps to protect the fish from bacteria, as well as Velvet.

The salt also aids other treatments on your fish in its healing process.

Again, when adding the salt, do it gradually with about one teaspoon of aquarium salt per gallon (3.8L) of water every 3-4 hours, so that your fish can slowly adapt to the change.

If used correctly, salt can be a terrific cure for this disease.

However, if your Betta fish is not the only inhabitant of your aquarium, do check that all other creatures – plants included, can survive with the salt present.

Additional Measures

Usually, after the three steps and the salt treatment, a dark, saltier, and hotter environment will kill the oödinium.

However, in some serious cases, if these treatments do not help, you can consider additional measures such as copper sulfate or malachite green.

Do remember to remove carbon from your filter system when adding these treatments, as the carbon will minimise the effectiveness or remove the medication, which would waste all your efforts of treating the Velvet.

Copper Sulfate

For this treatment, you would need to follow the manufacturer’s instructions, but a proper treatment usually lasts 10 days.

However, you need to ensure that the copper is used only on your fish, and not plants or any other organisms in your tank, as this medication can be toxic.

Thus, it would be best to do this treatment in a quarantine tank for safety reasons.

Also note, as Betta fish usually prefer a pH level below 7, do use copper sulfate with caution as it can further lower the pH level, which can disrupt your pet’s living conditions.

Malachite Green

Another alternative to copper sulfate is malachite green.

Just like copper sulfate, malachite green can also be toxic, but its toxicity is influenced by higher temperatures and lower pH levels.

Hence, this medication should also be used according to the manufacturer’s suggestions.

Do exercise care when using this medication as it can stain your clothing, skin, and even the tank. Thus, it would be best to use this treatment in a quarantine tank.

When using this treatment, even if the Velvet may seem to be gone, do ensure you continue treatment religiously according to the suggested number of days, as the parasites could still be living in your fish or the water.

One thing to note would be to use this treatment in a dim or dark environment, as the malachite reacts with light. However, weirdly, this information is usually not stated, so do remember to use it right.

Preventing Velvet

Whether you are a new Betta owner or an owner who has just treated your pet, I’m sure you would want to prevent this disease from happening or recurring.

Now that you have learnt about the causes of this disease, the prevention measures simply need to reduce or eradicate the causes as much as possible.

Thus, a few preventative measures you can take are:

  • Ensuring your pets have a nutritious diet – live food is good for making them work for it (for Betta fish, as they are carnivorous, you should be giving them plenty of meats)
  • Monitoring the water in terms of temperature, pH levels, and overall cleanliness (best to do regular water changes to keep the water fresh and clean)
  • Avoid stressing your fish as it can increase the chances of getting Velvet (the usual stress factors are the water environment and flaring – which is an act of intimidating other fishes or oneself if it sees its reflection)
  • Don’t overcrowd the tank (too many inhabitants can also stress your Betta as they need their space)
  • Quarantine new fishes for 2 weeks before introducing them to the tank
  • Disinfect new objects or plants



Velvet is one of the most deadly Betta fish diseases. My past experience in treating Velvet only seems to work if I use the blackout, higher temperatures, and copper sulfate together.

Recovery isn’t always guaranteed as well. A painful lesson especially if you have an expensive betta fish.

Therefore prevention is always better than cure.

I know this disease is quite terrifying, but I hope this guide helps both you and your fish!

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