Anchor Worms in Betta Fish: Symptoms, Treatment, Prevention

betta anchor worms treatment
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Betta fish are beautiful but can be a sensitive fish breed, especially if you’re keeping wild bettas.

This makes them prone to various ailments and conditions, such as popeye, fin rot, ich, or my worst enemy, velvet.

Most of these ailments are easy to spot and treat.

However, some conditions in betta fish are not so common, one of which is anchor worms.

Anchor worms on betta fish are one of the least common conditions among aquarium fish.

However, once you spot anchor worms on your bettas, you must quickly treat them and take preventive measures.

This article is a guide to symptoms, causes, treatments, and prevention of anchor worms in bettas.

What are anchor worms?

Despite the nature of their name, anchor worms are not actual worms but crustacean parasites.

The scientific name is “Lernaea cyprinacea.”

They’re indigenous to Eurasia and belong to the family Lernaeidae. They’re called “anchor worms” due to their “anchor-like head.”

A young anchor worm has a long body with a pale white/greenish/reddish colour.

Like all other parasites, anchor worms attach themselves to the body of betta fish to suck its blood.

Female worms use the blood they suck from their host (bettas or other fishes) to nourish their eggs before they release them in the water after maturation.

Anchor worms prefer the head section of betta fish to attach as it’s challenging for the betta fish to remove them there.

Like many other parasites, anchor worms can’t live without their host and immediately die after separation.

Thus, detaching them from the body of your betta fish is not enough; you have to eliminate them from your aquarium.

Infected fish can be a carrier for anchor worms to enter your aquariums, so quarantine all plants and livestock before putting them in your main tank.

What causes anchor worms in bettas?

As mentioned earlier, anchor worms in betta fish are uncommon – they can even be considered rare.

However, it doesn’t mean they can’t affect your bettas. When left untreated, they can cause a severe infection in your betta’s skin.

Following are some potential causes of anchor worms in betta fish:

The addition of infected fish to your aquarium of betta fish

Wild-caught fish are the most susceptible to anchor worms and are loaded with many parasites and diseases.

This is because wild-caught fish lives in natural water bodies such as rivers and lakes. This is the same habitat where anchor worms live too!

That’s why wild-caught fish have a greater tendency to get infected by anchor worms.

When you add untreated and unquarantined fish to your aquarium, parasites such as anchor worms can spread to your betta fish and infect them quickly.

If you are fond of keeping wild-caught betta fish like me, only add them to your aquarium after undergoing a proper treatment such as deworming.

Are you planning to keep wild-type betta fish?

Consider purchasing home-bred wild bettas as other hobbyists are likely to have dewormed the wild-caught bettas, and its babies are likely to be free from anchor worms.

Otherwise, you’ll need a spare hospital quarantine tank to treat any new additions to your tank.

Adding infected plants to your aquarium

Plants can carry their anchor worm larvae that will grow to attach themselves to a host (your bettas).

Anchor worm larvae are too tiny to see with the naked eye.

Therefore, it doesn’t mean they’re not present if you cannot see any larvae on the plant.

Anchor worms are highly contagious parasites that can spread from infected plants to healthy betta fish.

So, before adding plants to your betta fish aquarium, remember to treat them with aquarium salt and ready-made solutions to remove any anchor worm larvae and other parasites/bacteria that might be present.

Plus, you should purchase tissue culture aquarium plants – something I wish I did a long time ago.

Do you want to know what’s worst than parasites or diseases?


But that’s for another post.

Poor water conditions in the aquarium

Poor water conditions impact the immune system capabilities of betta fish and promote the nourishment of anchor worms.

Poor water conditions are a suitable habitat for anchor worms where they can thrive, reproduce, and spread quickly.

Thus, it’s always recommended to consistently check the water quality in your aquarium with a test kit and perform water changes regularly.

Besides these causes, any action that can introduce anchor worms in your aquarium could be the cause of anchor worms on your bettas.

Symptoms of Anchor Worm

There are about 5 symptoms of anchor worms that I know of, though they are not clear signs of anchor worms.

A clear sign of anchor worms is to see the anchor worms on your bettas’ bodies.

Seeing anchor worms on your bettas’ bodies

If you look closely, you can see anchor worms on your bettas’ bodies.

The average size of an adult anchor worm is around 0.8 inches (2cm), and its ends are split into 2. Most of it might be buried under your bettas’ skin.

anchor worm
Credit: WikiMedia Commons

When you look at the body shape of anchor worms, you’ll notice that their head has four appendages, divided into two sets based on their function.

One set of appendages serves as the “anchor” to attach to the skin of betta fish.

The other set of appendages acts as a covering for the worm’s mouth. These appendages cover the worm’s mouth during non-feeding periods.

As mentioned, anchor worms can have any of the following colours white/greenish/reddish hue.

Besides visibility, the other signs and symptoms of betta anchor worm are as follows:

Scratching against aquarium decorations

If your betta fish appear to be scratching their bodies against any solid object in the aquarium, it may be a sign of anchor worm infection.

They may do so to get rid of the anchor worms embedded in their skin.

It can also be a response to ich, velvet, columnaris, gill flukes, or just stress.

In any case, you should start looking for the presence of anchor worms so that you can quickly begin treatment.

Inflammation and soreness

An anchor worm infection can cause inflammation and soreness in the skin of your betta fish.

While attaching to the betta’s body, anchor worms try to embed themselves in the skin, which can result in sores and bleeding.

The penetration site on the skin where anchor worms try to attach themselves can be an inflamed mass.

In many cases, betta fish rub or scratch their skin against solid objects in the aquarium to eliminate the worms. They might get sores or develop inflammation by doing this.

If left untreated, soreness could become a severe infection that can cause ulceration in the skin’s infected area.

Therefore, you should regularly check your betta fish for anchor worm infections.

Malfunctioning of the respiratory system (breathing difficulties)

In some cases, anchor worms penetrate so deep into the betta fish’s skin that they may infect the internal organs, especially the respiratory system.

Betta fish with malfunctioning respiratory system experience shortness of breath, which you can take as a sign of breathing difficulties.

You can visibly see your betta breathing heavily and going up to the surface for air more often.

If your betta fish can’t breathe properly, you should examine their skin for possible anchor worm infection.

Other possible reasons for breathing difficulties could be columnaris, gill flukes, or ammonia poisoning.


If your betta fish has anchor worm infection, they may appear lethargic.

Swimming, hiding in aquarium decorations, and showing active behaviour may not appeal to them.

Your betta fish may experience a loss of appetite, and its body might get skinny over the weeks.

Despite these being common symptoms of anchor worm infection, you must still confirm the presence of anchor worms on your betta fish body before treating it.

The reason for this is that most of these symptoms can appear when betta fish are sick due to any illness other than anchor worms.

For example, betta fish may feel lethargic due to depression or a temperature shock.

Similarly, breathing difficulties can also arise due to ammonia poisoning or a respiratory disorder.

In that case, it wouldn’t hurt to confirm that anchor worms have attached before proceeding with treatment.

Treating anchor worms in bettas

Many treatment methods can be used to cure betta fish infected with anchor worms.

Manually remove the anchor worms

The most effective treatment for an anchor worm infection is removing the attached worm by hand or aquarium tweezers.

However, this can be risky as you may cause damage to your betta fish’s skin if the anchor worms are penetrated so deeply.

Therefore, experts recommend not performing on-hand removal of anchor worms as the first step, more of a last resort.

You can perform many other treatments to get rid of anchor worms, such as aquarium salt, potassium permanganate, or medication.

These treatments improve the immune system capabilities in your betta fish, weaken the hold of anchor worms on the betta fish’s body, and speed up their recovery process.

Potassium Permanganate treatment

Potassium permanganate is an effective disinfectant for betta fish suffering from anchor worms.

It makes it easier to remove anchor worms from betta fish easier by weakening their hold on the body.

In most cases, anchor worms have difficulties attaching to your bettas’ bodies.

Once unattached from the skin, you can scoop them out from the water.

Here are the 8 steps needed to treat anchor worms with potassium permanganate:

  1. Use a hospital tank instead of dosing directly into your betta tank.
  2. Potassium permanganate is powdered, so you must mix it in water before dosing. For that, take a small bucket and fill it with aquarium water.
  3. Now, take out the potassium permanganate powder from its bottle and dissolve it following the manufacturer’s instructions. If unavailable, use 25mg for every litre.
  4. Take a large container and add 10 litres (2.65 gallons) of aquarium water and mix 250 mg of potassium permanganate. This is for serious cases only, and I don’t recommend you try this first.
  5. Make sure the temperature of the hospital tank is the same as your aquarium. Have 1 hospital tank with just aquarium water and an airstone ready.
  6. Now start the potassium permanganate treatment. Take out your betta fish from the aquarium and bathe them in the potassium permanganate container. Each betta fish should stay in the container for 5 minutes.
  7. If you notice your betta fish struggling or trying to jump out of the container, take her out and place her in the container filled with only aquarium water. If you don’t notice any struggle, continue to bathe betta fish until all fish are treated.
  8. After bathing each betta fish, don’t forget to place her in the container filled with aquarium water to rinse any extra potassium permanganate from her body before putting her back in the aquarium.

Potassium permanganate effectively kills immature anchor worms and makes the mature ones lose their grip on the skin of betta fish.

If you notice anchor worms penetrating deep down in betta’s skin, perform potassium permanganate treatment more than once.

Besides potassium permanganate, you can also use Dimilin (a powerful disinfectant) to remove anchor worms.

Dimilin disrupts anchor worms’ growth and kills immature and unattached mature anchor worms.

The suitable amount of Dimilin for anchor worm treatment is one teaspoon in 500 gallons of aquarium water – again, you should follow the manufacturer’s instructions.

Aquarium salt treatment

An aquarium salt treatment is another effective method to deal with anchor worms.

You can prepare an aquarium salt bath just like a potassium permanganate salt bath to treat your betta fish for anchor worms.

You can also directly mix aquarium salt in your aquarium, though I don’t recommend it.

I covered how you can do aquarium salt treatments for betta fish, so do check it out.

You can continue with aquarium salt treatment for a few days to weeks, depending on the number of anchor worms in the aquarium and how bad the infection is.

Also, remember to perform 30% water changes weekly.

Removal of anchor worms by hand

After potassium permanganate and aquarium salt treatment, you can remove any left anchor worms by hand.

Use a net to bring your betta fish out of the water, and use tweezers to pull anchor worms out of their skin carefully.

Try to grab them near their heads.

Don’t keep your bettas out of the aquarium water for too long, and remember to put them back in the tank to breathe.

Preventing anchor worms in bettas

You can follow these helpful to prevent anchor worm infections:

  • Only add new fish to your betta fish aquarium if they’re quarantined for a few weeks in a quarantine tank and checked for anchor worms (and other diseases). You should quarantine them for at least 1 month as the life cycle of anchor worms lasts up to 25 days.
  • Perform regular water changes, perhaps 25% to 30% weekly.
  • Keep the water quality high to prevent your betta fish from being stressed out and vulnerable to diseases and illnesses.
  • Check your betta fish for anchor worms regularly. If you notice even a small number of anchor worms attached to betta’s body or floating freely in the aquarium, immediately take treatment and prevention initiatives.


Anchor worm infections are rare in betta fish, but when it occurs, they can seriously impact your bettas’ health.

Therefore, you should be aware of preventive measures, and treatment procedures for anchor worms should the need arrive.

And remember, always quarantine everything before you add to the tank, and have a spare hospital tank.

I hope this post has been helpful for you in identifying and treating anchor worms.

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