Aquarium Fish Diseases

Treatment for Camallanus worms in your Aquarium

Camallanus worms. Even the name gives chills! Infectious, dangerous, and downright disgusting. They can be VERY difficult to remove and losses can be high if not treated early.

So: What exactly are Camallanus Worms? A parasitic nematode that lives in the intestinal tract of fish, and can be seen as one or more red worms protruding from the fish’s anus.

Yeah. It’s pretty nasty.

Symptoms of Camallanus Worms

A fish infected with Camallanus worms Do you notice that the fish exhibits a very skinny appearance and tight fins? Is very sick.

The worms are hoarding the nutrients that should go to the fish.

Other symptoms may include:

  • Long, thick white poop (mucus from irritation of the intestinal lining)
  • Swollen/irritated anus
  • Weightloss
  • bad coloration
  • Minor abdominal bloating
  • loss of appetite

By the time you see the real red worms hanging off the fish, you have a serious and advanced infection on your hands.

This fish from the video shows the thick white poop associated with intestinal irritation from Camallanus worms:

The adults can also multiply to the point where the fish cannot remove them and they end up dying.

Not only that, but the presence of these worms damaging the inside of the fish can lead to secondary bacterial infection and internal bleeding.

That’s why it ‘s so important to treat fish, and treat them early.

And a preventive treatment for new fish is a very good idea, especially for species that seem especially prone to this infection, including:

Fortunately the disease is not as common in goldfish, but they can still get it if they are housed in infested waters.

How to treat Camallanus worms?

The entire system needs to be treated once you have a confirmed infestation. Why? Because this parasite contaminates everything in a matter of days by producing dozens of microfilariae (basically young worms) that infect tank water and surfaces.

Once you see a fish that has it, you must assume that all fish have it too.

That means there is no point in mounting a hospital tank.

Choose the best medicine

The best options include:

  • Medications containing Fenbendazole
  • Medications containing flubendazole
  • Treatments containing Levamisole

So which one is the best?

Of the available treatments, the cheapest option by far is the Panacur C canine dewormer. It is 22% Fenbendazole.

(I will explain how to use it in the recipe below)

  • NT Labs NT480 Anti-Fluke & Wormer is effective, available and easy to use. But I see it as an overpriced flubendazole marketed to aquarists, and sold as a water treatment instead of a premix feed or something.
  • Levamisole is also good, but can be hard to find. For what it’s worth, there is talk that parasites are becoming increasingly resistant to Levamisole.
  • Anthelmintics such as Flubendazole and Fenbendazole work very well to eliminate worms from pets.

Now some may suggest the popular treatment, API General Cure. The effective ingredient in this product against this parasite would be Praziquantel.

But the problem with using Praziquantel as a weapon is that Camallanus worms in general have become incredibly resistant, making them much less likely to work and as a result there are many people online reporting that the worms survive the treatment.

Some people like to pair Epsom salt and garlic as a treatment, and it can help, but it’s better as a preventative before having fish with worms (in my opinion).

That’s because these worms are so hard to get rid of, and by the time you see them it’s pretty serious.

Although I generally try to avoid medications in my aquarium when possible, they are sometimes necessary and very helpful – even life-saving – for our pets.

The good news is that most of these drugs have very low toxicity to fish.

You can dose the medicine into the water directly, but I prefer to go the medicated feeding route. This is because it has less impact on the biological flora of the aquarium.

It is possible for a fish in advanced stages of the disease to die during treatment. This is because when the adult worms die in the fish, they can decompose and poison the fish. The dying fish were already too far advanced. But it is necessary to continue the treatment to save the remaining fish.

Make a medicated feed

Keep in mind that if your fish are at the point where they are not eating, water treatment is the only option for you, so don’t bother with a medicated feed.

It’s time to make the medicated feed. This is a good recipe for a Fenbendazole based food.

For the fish it will taste very bad. This thing tastes super gross to them. So you are going to need to make the food as delicious as possible with foods that are palatable to the fish and flavor enhancers.

Recipe to make the medicated food:

  • Put 2 thawed bloodworm cubes or 2 thawed beef heart cubes into a small bowl.
  • Dissolve 1/8 teaspoon of Fenbendazole 22% granules (crushing it well with a spoon is a good idea) in Garlic Guard (to mask the foul taste) and add this mixture to food.
  • Use 1 teaspoon of Seachem Focus to bind the medication to the food (optional but makes the food MUCH more effective) and mix it all together.
  • Let sit for 1 hour before feeding.

Feed the fish 1 time per day for 3 days in a row, then repeat after a week for 3 weeks in a row. Don’t feed anything else on the days you do.

Be aware that after feeding, the fish may start to shed worms after the first hour of eating the food (gross but good).

Perform daily water changes

Understanding the life cycle helps us know how to deal with this problem.

The drugs normally work by paralyzing the adult parasites rather than killing them. The fish is then able to excrete them into the water.

Vacuuming the gravel and doing large, frequent water changes will help remove the eggs, which are resistant to medicine. It is especially important to remove fish feces.

It’s much easier to do this in a bare bottom tank, like a hospital/quarantine tank, but if your main tank is infected, you’ll have to do it.

Cleaning aquarium filters is also a good idea.


It is true, like many things, prevention is much easier than treating a problem. So how do you make sure your fish don’t get infected with this disease?

The only sure way to prevent these Camallanus Worms from infesting your tank is to quarantine all new fish.

Treating new fish with EPSOM salt/garlic as a preventative is a good idea, to help the fish eliminate small parasites before they become adults.

Fish showing symptoms of worms hanging off their bottoms should be medicated.

Also avoid feeding your fish tubifex worms, as they are vectors for many nasty parasitic diseases that afflict our fish friends.

Conclusions about the Camallanus Worms

Yes, Callamanus worms are nasty things. But, if detected early, fish health can be restored by applying treatment at the right time.

I hope this helps point you in the right direction for treatment.

Do you want to share your experience or advice?

I invite you to leave a comment below!


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