Camallanus Worms Infection

What are Camallanus Worms


Camallanus worms are thin thread-like pink-brown worms having only a few millimeters to around 1,5 cm long nematodes. They are internal parasites that infect both fresh and saltwater fish and organisms. Camallanus worms settle at the host’s intestines and feed off from the host’s blood.

The Camallanus infection is mostly associated with livebearer fish such as mollies, platies, guppies, swordtails and so. But they can infect any kind of fish in case only one infected fish is existing in the aquarium. Gouramis, discus, plecos, cories and angelfish are also commonly got infected with Camallanus worms.

Life Cycle

Camallanus worms reproduce by giving birth to live offspring. Females incubate eggs internally and release offspring while they hatched. The released first-stage larvae mostly require a transition host to develop to the second larval stage before infecting a fish. These transition hosts are mostly small aquatic creatures such as copepods, nauplii, daphnia, rotifer, tubifex worms, other aquatic worms, etc. The larvae complete the second and third development stages in this transition host’s body. While the fish eat the infected transition hosts the camallanus larvae infect the fish develop to adult and reproduce.

The latest studies under aquaculture conditions showed that the intermediate/transition host is not always necessary and a first-stage camallanus larvae can be ingested directly by the late host (fish) and develop to later stages in the definitive host’s body. The studies also showed that free-living first-stage larvae can survive for around 4 weeks or so in lack of host availability. Thus, the treatment plans should cover at least one-month period to kill off the free-living infectious larvae that may exist in filters, substrate, or in the water column as well as in the individually infected fish.



Most aquarists can’t easily notice the parasite or symptoms of a Camallanus worm infection due to its long development period. Quarantining fish will not work well also for the Camallanus infections due to its long incubation period. It can take up to 6-12 weeks for Camallanus worms to develop to the adult stage and finally the worms can become dangling out of the fish’s anus. At this stage, an average hobbyist can only notice the infection.


Infected fish may become frail despite the good and enough feeding. The feces of fish become white and slimy due to intestinal damage which can be confused with an internal infection or improper feeding. This makes the diagnosis harder and in some cases leads to wrong treatment. In case the white and slimy feces symptom is observed with a combination of losing weight, becoming shy and staying out of the school (for the schooling fish), lying on the bottom, or making rotating movements symptoms then, it may refer to Camallanus cotti infection.

Light infections can stay undetected for long periods and fish may never show symptoms especially if the aquarium has ideal water conditions for the fish. Juvenile fish are more likely to show signs of reduced growth.

Symptoms Summary

  • Shaking or shivering
  • Unexpected and unexplained deaths
  • Weight loss
  • Becoming shy, staying out of school
  • Refusing food
  • Sunken stomach
  • Bloated body, surged scales
  • Lethargy
  • White, slimy feces


There are only chemical treatment methods available for the Camallanus infection since it is not possible to manually remove the parasite and kill all the freely remaining ones in the aquarium or the fish body. Hereinafter, some effective treatments are listed which may help you to fight back and overcome the infection safely.

Whether it is a parasitic or bacterial infection it is always important to dose the correct amount of chemical/medicine to treat the fish safely. If an insufficient dosage is applied for the treatment, it will just retard the infection and strengthen the bacteria/parasite against the treatment and won’t work at all. However, if the dosage is high, this may lead to loss of livestock according to their tolerance levels. So, it is suggested to dose at the correct amount as per the below dosage amounts.

It is reported that Camallanus worms have developed immunities to common de-wormers on the market which have reduced effectiveness or do not work at all. Some of those mentioned in the online sources are Prazi medication, Praziquantel powder, Droncit (Prazi), Prazipro, Trichlorfon, Metronidazole and possibly fenbendazole.

Due to most of the treatments are not very effective, in the below only the most effective treatment method is compiled from the common treatment practice in aquarium society. Please note that the responsibility for possible damages that emerged from the suggested treatments is under user risk.

Levamisole Treatment

Levamisole is a de-wormer in which mostly used for cattle, dogs and cats. It is a hydrochloride salt and anthelminthic medication. Levamisole is absorbable from the skin of the fish and does not require in-food dosing. The directly dosing feature of Levamisole makes it more practical for the average hobbyists. Since it is also an effective treatment it is the most popular treatment for camallanus infection.

The treatment consists of 1 initial and 1 or 2 follow-up dosing with large water changes. For better results, it is important to follow the treatment instructions in the below section. Also please note that it is better to flush the water to a restricted empty area that it can dry out with no contact to the public water system or reach of birds for preventing the spread of Camallanus Worms.

Cautions: Levamisole is not suitable for use with invertebrates, crustaceans, mollusks. Levamisole may also affect fish such as plecos which have an exoskeleton.


The suggested dose for Levamisole HCl is 13 ppm. There are various levamisole medicines available in the market which may contain different amounts of Levamisole. Thus, it is important to check the total amount of Levamisole from the datasheet of medicine and calculate the dosage accordingly. It is easy to calculate once you know the total Levamisole content in the medicine. The calculations below are for reference and the correct dosage must be calculated according to the water volume of the treatment tank.


1 gram of Levamisole = 1000 mg of Levamisole
1 ppm of Levamisole = 1 mg of Levamisole in one liter of water
13 ppm of Levamisole = 13 mg of Levamisole in one liter of water
13 ppm of Levamisole = 1300 mg of Levamisole in a hundred liters of water
Required Dosage (mg of Levamisole) = 13 mg of Levamisole x Water Volume in liter

Levamisole Application – 1

Step – 1: The best practice is to treat all infected fish in the main tank instead of treatment in a separate quarantine tank due to the worms remaining freely in the main tank which will infect the fish again. First, remove all the decorations and any unnecessary tools from the tank and bleach them then dry them out separately without letting the wastewater go into the public water system. Also, remove the UV filtration and Active Carbon from the filtration before starting the treatment.

Step – 2: Reduce the water level to half. Keep aeration and filtration running and increase aeration.

Step – 3: Calculate the water volume and then the required dosage as per the above calculations. Add the required amount of Levamisole to the aquarium water gradually. Keep everything working and feed the fish with high-quality food if they are eating. If possible, feed with garlic-containing fish foods to help the fish expel the worms more easily. During this period the worms should begin to die and be expelled from the fish.

Step – 4: Watch the fish for any symptoms of bloating. If there is any bloating that may be a sign of internal infections due to the dead worms decaying inside the fish body. In that case, immediately start treatment for the bacterial infections and use Epsom salt to help fish digestion. (Bacterial Infections and Treatments)

During the 3 days following the first dosing, fish may become lethargic and sink to the bottom of the tank and don’t move too much. They may refuse food on the first day and then they will start accepting little amounts. It is important to feed the fish with small amounts and test them eating without letting uneaten food remain in the tank bottom. Remove any dying fish and dry them out and dispose in the trash or bury them. Do not flush them into the wastewater system.

Step – 5: Following the 3 days, clean the filters and media, make a 50% water change, siphon the gravel and fill up the tank to the normal level (equivalent to 70-75%). If possible, increase the water temperature 1-2 °C for the following 3-4 days to prevent post-treatment ich infection due to any possible immunity drop of the fish. Keep watching for any signs of bloating and treat as required.

Step – 6: Since Pregnant worms contain eggs and these eggs may hatch in case the dead worms are perfectly removed from the tank after the first treatment it is essential to make 1-2 follow-up treatment. Feed the fish with high-quality fish food after the treatment to increase and support immunity. After 3 weeks repeat the same treatment. Make the third follow-up treatment for better results.

Step – 7: Change and dispose of the filter sponges and wools after the third treatment cycle or treat these materials separately for 2 more cycles (6 weeks) with a double dose if you are intended to use them again.

Levamisole Application – 2

Step – 1: Remove all fish in a separate treatment tank with no decoration, sand or gravel.

Step – 2: Follow Application-1 in this separate treatment tank (3 Treatment Cycles).

Step – 3: In the main tank, apply double the treatment dose and make sure all the worms are dead. Clean and bleach all decorations plants and tools. After 3 days make a large water change.

Step – 4: Cycle the main tank empty and repeat the treatment with a double dose for 2 more treatment periods (3 treatment Cycles in total)

Step – 5: Move the fish back into the main tank. Clean and bleach the treatment tank, equipment, tools, etc. by paying attention to prevent camallanus infection spread as mentioned above.

Levamisole Supporting Treatment

In some sources, it is suggested that dosing Dylox 80 (Active Ingredients: Trichlorfon) for 2 weeks after the initial treatment water change will kill the eggs remaining in the dead worms immediately. But there is no dose information provided specifically for this chemical.

For reference, one of the active ingredients of Mardel Clout is Trichlorfon and the dose recommended is 9.5 mg for 38 liters of water equivalent to 0.25 ppm.

  • Please note it is reported that Trichlorfon is a very strong and neurotoxic chemical that may also cause cancer.


Since there is nothing that can suddenly appear from thin air, camallanus worms or any other type of infection must be first introduced to the aquarium somehow. The infection source can be a new fish, live or frozen live food, open-air ponds or aquariums where the birds and insects have the reach and infect with the camallanus worms. Thus, it is vital to get new fish and live or frozen foods from trusted sources, quarantine new fish, and keeping the tanks closed to prevent the reach of birds and insects. These measures are easy to be taken for anyone. In most cases, they will prevent any infection but even if they are all done properly, the fish may still get infected. With that possibility, good observation of fish becomes critical to diagnose the problems on time and start treatment immediately. Since we are keeping our pets, we have the responsibility to provide them good care and environment.

Image Url:

0 0 votes
Rate This Page
Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments