What Is A Camallanus Worm-A Complete Guide

When I think of worms, I think mainly of a nightcrawler. There are also the red worm, the glo-worm, and a vast variety of plastic/rubber worms. But, as everyone knows, these are the types of worms that you would purchase to go fishing at a lake, river, stream, or pond. Today, we are going to be talking about a completely different type of worm. One that is only found in aquariums. It is the camallanus worm. 

What Is A Camallanus Worm?, Camallanus worm is a genus of parasitic roundworms. There are a couple different types of camallanus worms; camallanus cotti (the most popular), camallans fotedari, and camallanus trispinosus. 

There is, however, a promising drug that is gaining recognition in the treatment of the camallanus worm. Fenbendazole is a treatment for this infection in freshwater tropical fish. There are different types of medications where this is the main ingredient, including a fish feed that you can make in your own kitchen. 

In this article we are going to discuss the lifecycle of the camallanus worm, how to prevent them, how to get rid of them, how to treat your fish, and much more. So if you have an aquarium with freshwater tropical fish, you are going to want to take a look at the rest of this article. It could save the life of your fish.

Life Cycle of the Camallanus Worm

There are 3 phases in the life cycle of the camallanus worm.

  • A free-living stage
  • A series of molts- worm infects a crustacean
  • Another molt- takes place in the host (fish) – only if the fish eats the infected crustacean. 

After the female mates she will produce first-stage larvae, in large numbers. The fish will then expel the waste, which will carry the larvae out to the environment (aquarium). These little larvae will settle on the rocks, gravel, and any other decorations in your aquarium. They will reel in the crustaceans with a simple little wiggle. Once the crustacean swallows the enticing larvae, the larvae will move into the stomach to feed and to grow. 

In approximately a week’s time, they will have molted inside of the crustacean, twice. It is now what is called a third stage larvae. If the crustacean is unluckily eaten by a fish then the 3rd stage larvae will become active again. Inside the belly of the fish it will eat and grow, molt twice more, and become the mature male or female camallanus worm. 

This whole life cycle, at 77 degrees, will only take about one month. Camallanus cotti can skip the intermediate (crustacean) host, and go straight to the final host (fish). The camallanus are the red worms that you see coming out of the anus (vents) of the infected fish.

How Do You Detect Camallanus Worms

Because the camallanus worms are so small, they can be hard to detect. The optimal way to detect them is to learn/know the signs and always monitor your tank. The fish can be heavily affected or just slightly affected by the camallanus worm. No matter how healthy your fish, be sure to keep one eye out for these signs;

  1. Red, thread-like worms coming out of the anus of the fish. 
  2. Abdominal bloating
  3. Disinterest in their food
  4. Ulcers or pop-eye
  5. They do not like the light

A lot of avid aquarists associate the camallanus worms with guppies, angelfish, mollies, discus, and loaches. Most types of aquarium fish can be infected however.

A mature camallanus worm is going to be a couple of millimeters long and will be very easy to detect because it is red and will be floating out of the fish anus. Some other symptoms, which we listed above as well; bloating, not eating, and wasting. 

How To Treat the Camallanus Worm

As with most anything else, there are many options for treating the camallanus worm that you have found in your tank/fish.

AnthelminticAn antiparasitic drug is absolutely necessary for treating your fish for camallanus worms. This drug will expel the camallanus worm or other parasites from the fish. 

There are also other medications that will paralyze the parasite, allowing it to be pushed out of the gut of the fish. Some of this sounds nasty, but it could very well save the life of your child’s pet fish. 
FenbendazoleIs a wide spectrum benzimidazole anthelmintic used against the parasites.
LevamisoleIs a synthetic compound that is used as an anthelmintic especially in animals, but also used in cancer chemotherapy.
Praziquantel Is a medication that is used to treat a number of types of parasitic worm infections (according to Wikipedia). It prevents newly hatched larvae from growing.

Within 24 hours of using any of the above medications you are going to have to do a complete water change and scrub down the rocks, gravel, and the other decorations in your aquarium. 

The anthelmintic medications listed above can be toxic to snails, so if you have any in your aquarium then you are going to want to take them out before you treat your fish/aquarium. They can also be toxic to fish if you do not use them exactly as the directions state. 

How to Prevent the Camallanus Worm

The best, and basically, the only way to prevent camallanus worms is to quarantine the infected animal. Camallanus worms infect crustaceans, such fish food should definitely be avoided. The only problem with this, if your fish is in an aquarium with other fish, you can not just quarantine the 1 fish because the rest of them are probably infected as well, just in a different stage. 

Unfortunately, there is really no other way to prevent the camallanus worm, if there is, it isn’t documented or stated anywhere that my research could find.

Can the Camallanus Worm Infect Humans

Camallanus worms are a parasitic nematode. They are very contagious among fish and should be taken care of as soon as you see them. Unfortunately, by the time you notice them the worms will have passed their reproductive stage. What this means, they may have already released microscopic larvae into the aquarium.

There has never been any reports or anything about camallanus worms being transferred from aquarium fish to humans. But do you remember that a fish aquarium is not a sterile environment. If you have an open wound it is recommended to wear a glove, because of the other bacteria that live in your aquarium.

It is more likely to NOT happen, but as a precaution cover the wound well and then wash with antibacterial soap when you are finished cleaning your tank. 

How to Choose the Best Treatment for Camallanus Worms

We discussed medications earlier in this article, but here is a little more information including making a medicated feed. 

Because this type of parasite can contaminate everything in just a few days you will need to treat your entire system. A complete water change and scrub down of all rocks, gravel, and other decorations that are in your tank. You are going to want to change your filter as well. This will remove any of the bacteria and infectious bacteria from the tank.

Once you notice one fish with camallanus worms you need to assume that all fish have some stage of the infection.

The best medication options:

  • Medication containing Fenbendazole
  • Medication that contains Flubendazole
  • Treatments that contain Levamisole

Your cheapest alternative is going to be a medicine called Panacur c Canine Dewormer. The main reason for this choice is because there is 22% Fenbendazole in it. Make sure you talk to your veterinarian to get the best option to administer to your fish. Because of course, you can not give it to a fish quite like you can your dog/cat.

You can check Panacur C Canine at Amzon here.

Wormer Plus is available, easy to use, and effective. This is sold as a water treatment rather than a food pre-mix. So it is going to be perfect if your fish are at the stage where they are not interested in or eating their food.

Levamisole is also effective but harder to find in the United States. There are suggestions that the parasites are becoming immune to this type of treatment.

There are some that may recommend or suggest API General Cure. API is a company that has a wide variety of products for aquariums. Anything from food, to test kits, and water treatment supplies. The effective ingredient is Praziquantel. But, camallanus worms have more or less become immune to the Praziquantel. You can check with your veterinarian if you have any other questions about API and the ingredients effectiveness. 

So people have used Epsom Salt/Garlic as a treatment. Others feel this is better as a preventative measure rather than a cure/treatment. There are other people who prefer to do the medicated feed route vs. treating the water. Adding treatment to your water can harm your scaleless fish and inverts. If your fish are still eating, it is safer to do the food treatment, then your other fish are not going to be harmed. 

There is also a medicated feed that you can make at home. However, if your fish are at the stage of not being interested in their food then you will have no option but to do the water treatment.

This recipe is Fenbendazole based and is going to be gross tasting to the fish. We will give you some ideas on how to make it taste better, so that they will eat it. 

You are going to need 2 cubes of dethawed frozen beef heart or bloodworms. You need ⅛ teaspoon of 22% Fenbendazole granules, ground very small, dissolved in Garlic Guard. Then you mix it with the bloodworms or beef heart.  Take 1 teaspoon Seachem Focus and mix it with the rest of the ingredients. This will help bind the medications to the food.

It is recommended that you wait at least 1 hour before you feed your fish. Your feeding schedule should go as follows: 

For the first 3 days, you will feed them the mixture once per day. Do not feed them anything else in those 3 days. Wait 1 week, feeding them their normal food, and then you will feed them 1 time per day for the next 3 weeks. Again, do not feed them anything else with or beside the treatment/mixture.

Within the first twenty-four hours of feeding your fish they should begin to pass/expel the camallanus worms. Then you are going to want to be diligent in cleaning your tank and the substrate on the bottom, daily.

It is going to be tedious work, but you want to at least vacuum the bottom of your tank every single day to clean out any eggs and fish feces. This prevents the eggs from hatching into the larvae and it removes the infected feces from the water. Every other day or every 2 days you are going to want to do a 25%-50% water change. This will help remove any bacteria and things from the water, and will aid in having cleaner water, than just with the vacuuming alone. 


The only real preventative measure that you have against the camallanus fish; quarantine any new fish you purchase. Then it will not spread to your already established tank and fish. It is recommended that you keep them quarantine for at least a week, if not 2, just to be on the safe side of the coin. 

Remember, it is harder to catch a light infection because it is in the early stages and you may lose some of your fish during the treatment process. It all depends on how soon you catch the infection, what stage it is in, and if you can get the medication in a reasonable amount of time. You want to begin the treatment process immediately.

Camallaus worms are a nasty parasite that infects freshwater aquarium fish. Look closely at your fish when purchasing them. If they have any cloudy/white or red thread-like stuff coming out their anus, DO NOT purchase them or any of the fish in that tank. It will almost always be camallanus worms that you are seeing.

Reminder: camallanus worms are more likely in angelfish, guppies, mollies, discus, and loaches. So if you want those fish in your aquarium, examine them thoroughly before you purchase them. Yes, other freshwater aquarium fish can get camallanus worms, but the above are the most often infected. 

So, choose carefully what fish you are going to put in your tank. If you choose any of the above then you may want to keep treatment on hand, just in case you notice camallanus worms. Then you will be able to treat them immediately, instead of a couple of hours after you notice them. 



I'm passionate about fish pets and love sharing everything I learn about them.

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