If you’ve seen a long, thin worm-like organism hanging off your betta fish, it’s almost certainly an anchor worm.
Anchor worms are a rare but serious parasite in home aquariums, and bettas can be targeted just as easily as any other fish.
But what should you do if your betta has got anchor worms? And are anchor worms really worms at all?
Here we will demystify the weird world of anchor worms and help you prevent or treat a potentially deadly infection.
What Are Anchor Worms?
The Anchor Worm (Lernaea cyprinacea) is not actually a worm at all but a type of contagious parasitic crustacean that often affects fish in aquaculture ponds.
Thankfully, anchor worms are relatively rare in aquariums, but they do occasionally affect tropical fish, including betta fish.
Are Anchor Worms Visible?
Anchor worms are macroscopic parasites, and in their adult form can be seen with the naked eye.
This makes them relatively easy to identify since the only other parasite large enough to see on aquarium fish is Argulus.
Also known as ‘fish lice’, their round, compact bodies look quite different from the elongated, thread-like body of an adult anchor worm.
Diagnosing Anchor Worms
Anchor worms are white, gray, green, or red in color and grow up to 0.8 inches long. The adult worms bury their heads into fish at various parts of the body, but especially around the base of fins, at the gills, and around the mouth.
In the early stages of infection, the anchor worm will be so small that it’s very difficult to see. The most common symptoms of their presence will be your fish looking agitated and scratching against rocks and gravel in an attempt to remove them.
As the anchor worms get bigger, you’ll see them hanging off your betta fish and they may also cause red or greenish sores of ulcers at the site of infection.
After some time, a betta fish hosting anchor worms may appear lethargic and struggle to breathe.
In acute cases, anchor worms can penetrate deep into the fish’s tissue and may even pierce their vital organs, causing the fish to become very sick, and refuse food.
In the worst-case scenario, a deep infection could cause your betta fish to die.
How To Prevent An Infection of Anchor Worms In Betta Fish
Fish diseases tend to be easier to prevent than to cure. Here are some ways you can prevent an anchor worm infection from taking hold in your betta tank:
Select Only The Healthiest Fish For Your Tank
Anchor worms are highly contagious and normally spread from one fish to another.
This means the best way to avoid anchor worms in your betta tank is to make sure the fish that you’re buying from the pet store are fully healthy and free from infections.
If you’re buying online, only buy from experienced, reputable sellers with glowing reviews.
Isolate New Fish In A Quarantine Tank
As an extra preventative measure against parasites and other fish diseases, some fish keepers like to isolate newly purchased fish for 2-4 weeks in a quarantine tank before introducing them to their main fish tank.
This allows an opportunity to see if the new fish develop symptoms of a disease before they have the chance to pass it on to others.
Take Care When Introducing New Plants
Free-swimming baby anchor worms, known as anchor worm ‘larvae’ have been known to hop a ride into a new aquarium via live freshwater plants that were growing in a tank with infected fish.
This means that if you’re obtaining new aquarium plants from a tank that had fish in it, it’s safer to quarantine them in a separate tank without fish for 4 weeks before introducing them to your main aquarium water.
Since anchor worms are not the only type of pathogen that can be transmitted with the introduction of aquatic plants, it’s a safer bet to buy plants from tanks that don’t have fish in them.
This way the only pests that you could conceivably introduce with new plants are invertebrates such as snails!
How To Treat Anchor Worm Infections In Betta Fish
If your betta fish has an anchor worm infection it’s important to treat them as soon as possible, since anchor worms can reproduce and infect other fish within a matter of weeks, and deeper infections can also threaten your betta’s life.
Option One – Take Your Betta Fish To A Fish Vet
The preferable option for removing anchor worms is to take your betta fish to a qualified vet to remove them under sedation.
Since removing anchor worms on betta fish involves catching and holding the fish still while the worms are physically pulled out, it can be a considerably stressful experience for your betta.
Having this done by a trained professional will usually result in the least stress for your fish and the best chances of a positive outcome.
Of course, not all of us have a fish vet down the road from us, so some more experienced fish keepers might consider removing anchor worms at home.
Option Two – Removing Anchor Worms At Home
As I’ve indicated, removing anchor worms at home isn’t without its risks, and if you’re in any doubt about removing anchor worms yourself, I’d recommend contacting a vet.
Since I’m not personally a trained vet, the following advice is simply what I have learned from watching other people remove anchor worms.
If you choose to go ahead with the following instructions, please understand you do so at your own risk!
Catch Your Fish!
If you want to remove your anchor worms at home, the first thing you’ll need to do is catch sick fish.
Remember that your fish will already be suffering from the stress of having a parasitic infection, so be as gentle as you can with your betta to avoid creating unnecessary further stress.
Hold Your Betta Still
One of the most crucial skills for removing parasites by hand is holding your fish still without damaging them.
If your grip is too loose, you risk your betta struggling free, and if your hand is too tight, you risk stressing or even damaging your betta with your hand.
While some fish keepers prefer to remove parasites with their fish out of the water, others simply hold their fish at the water’s surface so their fish can continue breathing while the worms are removed.
Pull Out the Anchor Worms
With a pair of tweezers, grab the anchor worms as close as possible to the site of infection.
As soon as you have touched the anchor worms with your tweezers they’ll try to hold onto the fish even tighter, so the idea is to pull them out quickly, as soon as you have touched them to avoid their heads getting stuck in the fish.
Bathe Your Fish in Potassium Permanganate
In a small container bathe your fish in a potassium permanganate solution for 3-5 minutes at a strength of 0.04 oz to every 3 gallons of water.
Potassium permanganate is an inorganic disinfectant sometimes used for aquarium ornaments and plants, but it can also be used as a sterilizing solution for your fish!
It works well for sterilizing the sites of infection after you’ve removed the anchor worms from your fish and will also kill or weaken any small larval anchor worms that are beginning a new infection unnoticed.
Rinse Your Betta in a Clean Water Bath
After the potassium permanganate treatment, it’s time to rinse your betta in fresh, dechlorinated water for 5 minutes.
Make sure your baths for your betta are the same temperature as your aquarium (ideally 78-80 Fahrenheit).
(a) Return Your Betta to a Hospital Tank
Since your betta’s tank may still have larval forms of anchor worms in the water, it may be safest to release him back into a specially designated hospital tank for one month until the larval forms have died off and the risk of re-infection has passed.
If possible add a few plants or hiding places from a safe source to give your betta a place to hide and ease the stress that they’ve suffered through infection and treatment.
(b) Return Your Betta to Its Original Tank – Treated With Salt
If you don’t have a spare tank to house your betta, you could return him to his original tank after treating the water with aquarium salt.
Aquarium salt is effective at killing the larval stages of anchor worms, although it is less effective for adult forms.
Add salt at a rate of 1 tablespoon per 5 gallons every day for 4 days. On day 5, change 25% of the tank’s water with fresh, treated water, and repeat small water changes every day or two to gradually remove salt from the tank.
Keep an Eye on Your Fish
After you’ve completed your anchor worm treatment, it’s essential that you keep a close eye on your betta to make sure that the treatment went well and that no reinfection is occurring.
The wounds left behind from the sites of infection can also be prone to secondary bacterial infection which may need treating with antibiotics.
Repeat Treatment After One Week if Required
If it turns out that you missed one or two anchor worms, allow your fish one week to recover before attempting to repeat treatment.
Removing anchor worms can be very stressful for your fish, so shouldn’t be repeated too rapidly in succession.
Anchor Worms In Bettas FAQs
How Long Is the Life Cycle of Anchor Worms?
Anchor worms have a life cycle of 18 – 25 days in a tropical aquarium environment.
This may be slowed down at colder temperatures, and these parasites can even go completely dormant over the winter months in outdoor ponds when they’ll wait for temperatures to warm up again to continue their life cycle.
Can Anchor Worms Infect Humans?
Unlike internal fish parasites such as flatworms which can infect humans, anchor worms are external parasites and solely aquatic organisms and rely on fish and amphibians as their hosts.
Can Aquatic Frogs Get Anchor Worms?
Yes! Aquatic frogs such as African Dwarf Frogs can contract and spread anchor worms.
The treatment of frogs will be different from the treatment of fish. If you’ve noticed anchor worms on your pet frog, it’s best to consult a vet.
Can a Betta Fish Recover From an Anchor Worm Infestation?
If spotted and treated in time, mild anchor worms can be a relatively minor concern for a healthy betta fish.
In cases of fish that are infected more heavily, or in a betta that’s already old and frail, an anchor worm infection could pose a serious health threat to your betta’s health, and could, in rare cases, result in death.
Anchor worms are a potentially serious, yet thankfully rare parasite in betta fish aquariums.
Your best way to treat an anchor worm infection is by taking your fish to the vet, but if you’re willing to take the risk, you could also attempt to remove them yourself.
Once treatment is complete you’ll still need to treat the tank water with salt or parasite medication to remove any anchor worm larvae that remain in your tank so that it’s safe to return your beloved betta.
To find out about other diseases that could affect your betta, check out our dedicated pages here.