Anchor Worms On Betta (Causes, Symptoms & Treatment)

Last Updated on 2023-10-19

So, yourpotting anchor worms on betta fish is extremely uncommon. In fact, the chances of finding anchor worms on any aquarium fish are pretty slim. However, it does happen. If you think your betta has anchor worms, then soon you’ll find out how to treat them, as well as the symptoms, causes and prevention tips.

Key Takeaways:

  • Anchor worms are a type of crustacean called Lernaea, not actual worms, that can infest fish by attaching to their skin and burrowing in.
  • They are relatively rare in aquariums but can happen, and the most common causes of anchor worms are other infected fish or plants being introduced into the tank.
  • Common symptoms of anchor worms in betta fish include visible worm-like growths, rubbing or scraping against objects, redness, ulcers, sores, breathing difficulties, and lethargy.
  • To cure anchor worms, treatment involves manually removing them, using potassium permanganate, API General Cure, and adding aquarium salt to the tank. Quarantining the affected fish is also recommended.
  • Preventing anchor worms involves quarantining new fish or plants before adding them to the tank.

What Are Anchor Worms?

It turns out that anchor worms aren’t actually worms. They’re a type of crustacean called Lernaea. They infest fish by attaching to their skin and burrowing in, before latching on with their anchor like heads (hence the name anchor worms).

Luckily, anchor worms are extremely rare in aquariums and mostly happen in ponds. But nonetheless, sometimes they do happen. So what are the common causes of anchor worms?

What Causes Anchor Worms?

Anchor worms come from other fish and plants being brought into your tank. Because they’re highly contagious if a fish who is infected with them brings a few into your tank, they’ll multiply quickly and infect anything else in your tank, including your betta.

It’s a lot easier to spot anchor worms on fish than it is on plants. While adult anchor worms are most likely going to be transferred through fish, larvae are most likely to be transferred on plants. And the larvae is also a lot harder to spot.

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What Are The Symptoms Of Anchor Worms?

There is more than one symptom that is likely to show up when your betta is suffering from anchor worms. Luckily, on the whole, however, anchor worms are relatively easy to spot.

Here are the most common symptoms you can expect to see in a betta suffering from anchor worms.

Visible Anchor WormsAnchor worms can be seen as white, green, or reddish worm-like growths on the betta’s skin.
Rubbing/ScrapingAffected bettas may scrape or rub against objects as they try to detach the anchor worms from their bodies.
Redness/Ulcers/SoresAnchor worms’ presence can cause redness, ulcers, and sores on the betta’s body, typically near the affected areas.
Breathing DifficultiesIn some cases, anchor worms may burrow deeply and affect the betta’s internal organs, leading to breathing difficulties.
LethargySick bettas often display lethargic behavior, moving less and appearing less active than usual.

You’ll See Them On Your Betta

Because of their large size, anchor worms should be easily spotted on your betta. They can grow up to 0.8″ in length, which is clearly visible to the naked eye.

You’ll notice anchor worms by their white/green/red worm-like appearance if you look closely. They often look like they’ve also split in two on at the end, which is even easier to diagnose.

When looking for anchor worms you should check near the base of the fins, as this is where they’re likely to be.

Rubbing/Scraping Against Things

Another common symptom is that your betta will be scraping/rubbing against things. He’ll do this as he tries to detach the worms from himself. If you notice this, then you should check for anchor worms.

However, if you don’t see any anchor worms then it may be something else that’s causing him discomfort. Such as velvet, ich, columnaris or gill flukes.


You may also notice redness ulcers and sores on your betta. These are caused when he’s rubbing against things and begins to damage his body. If you notice any of these things it’s worth inspecting your betta. And if you see any anchor worms then you should begin treatment.

However, once again velvet, ich, columnaris, or gill flukes could also be causing this symptom.

Breathing Difficulties

It’s not uncommon for anchor worms to dig so deep they hit the internal organs of your betta. If you notice your betta has difficulty breathing, once again it may be worth just looking over him to see if any are attached.

If not then he may be suffering from ammonia poisoning, gill flukes, or columnaris.

Lethargic Behavior

And lastly, one of the most common symptoms when something is wrong with your betta. He may also appear lethargic. When bettas are sick they don’t move around as much. If you notice lethargy then there’s no harm in checking him over for anchor worms.

If you don’t notice any, then it may be temperature shock, depression or a whole range of betta diseases.

While anchor worms are pretty easy to spot, if you’re still not sure what your betta is suffering from then check out this article on all the diseases and illnesses that can harm them!)

How To Cure Anchor Worms On Betta Fish

Next, you need to know how to rid your betta of anchor worms. Here are the steps you should take to rid your betta of anchor worms.

Remember, that you should always add your betta to a quarantine tank if he is sick, otherwise you risk harming the other living things in your tank with the medicine you’re using. If you’re not sure here’s a guide on how to set up a quarantine tank.

Pulling Them Out

This is the most hands-on part. To pull them out of your betta you should:

  • Use a net to catch your betta and bring him to the surface of the tank.
  • Once your betta is out of the water use tweezers to grab the anchor worms and pull them out.
  • When pulling anchor worms out you want to grab as close to their head as possible. You also want to act quickly, and catch them when they’re not aware otherwise the head may stay in (don’t worry you can fix this).
  • Make sure you’re returning your betta into the water every once and while so he can breathe.
  • However, be warned that when you’re pulling them out if they are buried extremely deep you may cause a lot of damage to your betta.

Adding Potassium Permanganate

Next, you’re going to need to treat your betta with potassium permanganate. Potassium permanganate is a chemical used to cleanse ornaments and plants before they’re added to your tank. However, many aquarists also use them to disinfect fish that are sick with parasites or bacteria.

To treat you should follow the instructions on the bottle or speak to an expert. But here’s a rough guideline for you to follow:

  • If you’re going to be using potassium permanagate, you should only keep your betta in it for 5 minutes.
  • To use it fill 2 containers with dechlorinated water and add an airstone to the first container.
  • Once you’ve done that add 10 liters of water and 1 gram of potassium permanagate to the first one. (stick to this ratio if you want to use more water.) And fill the second one with dechlorinated water.
  • Before adding your betta make sure both bowls are the same temperature as his tank.
  • When the potassium permanagate is evenly distributed in the first container add your betta and let him sit in it for 5 minutes.
  • If at any time you notice him struggling or trying to jump out, remove him immediately and place him in the second container.
  • If he doesn’t struggle, then take him out after 5 minutes and add him to the second bowl. Make sure your timing is as accurate as possible.
  • Once he’s in the second bowl rinse off all the potassium permanagate and then place him back in his tank.

If the first treatment doesn’t clear up the anchor worms then you can perform a second treatment 1 week later. However, you should never perform a third.

Adding API General Cure

If you don’t want to perform a potassium permanagate dip then you can also try using API General Cure. API general cure is designed to treat parasitic infections, so it’s going to be perfect for anchor worms.

To use API general cure simply add 1 packet per 10 gallons of water, wait 48 hours add the same amount as the first time and then wait another 48 hours.

After the 48 hours are up you should perform a 25% water change, before adding activated carbon to your tank to remove any residual chemicals.

Adding Aquarium Salt To Your Tank

Once you’ve done this you should begin adding aquarium salt to your tank. This is going to help kill the remaining larvae and anchor worms in the tank so your betta won’t become their host again.

When adding aquarium salt to your tank you should add 1 tablespoon per 5 gallons of water. However, before adding the salt you should dissolve it in a cup of aquarium water.

When treating your tank for anchor worms you should add 1 tablespoon per 5 gallons per day. After 4 days perform a 25% water change. You can do this for up to two weeks.

After 4 days stop treating the tank. Here’s more information on aquarium salt.

Keep Your Betta In A Quarantine Tank

If your betta is the only fish in his tank then you should move him into a quarantine tank and keep him there for 28 days. An anchor worm life cycle is only 21 days, so if they don’t get a host they will all die in the tank.

After 28 days are up you can move your betta back into the tank knowing no anchor worms are going to infect him.

How Do You Prevent Anchor Worms?

The only way you’re going to be able to prevent anchor worms from attaching to your betta is by quarantining everything.

Anchor worms will be brought to your tank by other fish or plants. Because of this, you should quarantine any new fish or plant for a month before adding them to your tank. If within the month you start to notice anchor worms then you should begin treatment on your new fish

However, if after a month there aren’t any signs then you can add your fish to their new home.

Anchor worms on betta infographic

Are Anchor Worms Contagious?

Anchor worms are extremely contagious and if you notice any fish has them you need to remove them from your tank immediately. However, the good news is the chances of getting anchor worms in your betta tank is extremely rare.

But if you do notice them, then quarantining should be started immediately.

Are Anchor Worms Fatal?

If you treat anchor worms quickly enough then they shouldn’t be fatal. Of course, it depends on the state of your betta, if he’s already weakened by another illness then the chance of fatality is a lot higher.

Secondly, they can burrow so deep they can sometimes attach themselves to his internal organs, if this is the case then the chance of fatality is higher.

And lastly, if left untreated then the sores and ulcers on your betta caused by anchor worms are likely to succumb to a secondary bacterial infection.

So while anchor worms can be cured, if left untreated they will most likely be fatal.

If you’re lost on how you will take care of your Betta fish in the best way possible, this article can help you!

A Recap About Anchor Worms

Now that you know everything you need to know about anchor worms you should be more confident in your ability to treat them. Here are the main things you should remember:

  • The symptoms of anchor worms include anchor worms on your betta (they can be white green or reddish in color and look like a piece of string. Sometimes they’ll be split in two at the end.), rubbing and scraping on things, ulcers, sores, inflammation, redness, lethargy and difficulty breathing.
  • To cure anchor worms requires a mix of manual removal, treatment with potassium permanagate, treating the aquarium with salt, and if possible removing your betta to a quarantine tank for a month.
  • The best way to prevent anchor worms is by quarantining all new additions to your tank.
  • Anchor worms are highly contagious and if left untreated they can become fatal. So you must act quickly if you see them.
  • Luckily anchor worms are incredibly rare in aquariums, so the chances are your betta is suffering from something else.

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