Camallanus Worms: An Aquariasts Worst Nightmare

Last updated: September 28, 2022

The camallanus worm is a type of nematode worm that can inhabit the intestines of tropical and semi-tropical fish. This worm is quickly identified by the red paintbrush like worm tails that may protude from the affected fishes anus.

Camallanus worms can be avoided in your aquarium by quarantining new fish for several weeks prior to adding them to your tank, and watching carefully for worms, or even medicating the fish with a de-wormer. There is only one problem with this solution, is that camallanus worms can take up 6-12 weeks to develop to a large enough size or become frequent enough for the average aquariast to notice. Most fish infected slip through quarantine in 2-3 weeks time with no symptoms.

My Battle with Camallanus worms started about 1 year ago, when I purchased a Paradise fish, seemingly healthy, that passed through my QT tank after 16 days with no visible symptoms.
I had dewormed the fish during Quarantine with a flake food moistened and treated with Piperazine Citrate – the active ingredient in most dog and puppy wormers, usually very effective on most worms.
Camallanus is not, however, like most worms. Due to the fact that the commercial fish industry medicates fish at a massive rate, and pet stores also medicate fish, the Camallanus worm has, in some areas, developed immunities or reduced effectiveness towards some of the more common wormers on the market.

The paradise fish seemingly healthy, in my 10g tank, appeared with Camallanus symptoms approximately 3 months after I purchased her. During this time, I had moved all the livebearing fish out of my 10g aquarium and into my 75g aquarium, to grow more before selling.
The platies and guppies were of course, infected with Camallanus.
Within 3 months time, making this 6 months past the original infected fish arrived, many of the fish in my 10g and 75g tanks became infected. I lost several fish during the early stages, and all of my livebearing fish.
So, armed with the knowledge of what the worms were, I set out to purchase a worming medicine. The fellow at the speciality fish shop, suggested treatment with Trichlorfon, so I purchased enough for 5 doses, and followed instructions carefully.

Following treatment of all 5 doses, the camallanus were still spreading. Again, I returned to purchase another medication. This time, I had done more research, and had heard that Prazinquental worked wonders for these worms. So, I purchased a liquid form of Praziquental called Prazi-Pro, and began treatment. The container had a total of 12 doses. I used them all, again with no success. My third attempt at treating the worms was the Medine “Parasite Clear” by Jungle Labs, which came in a fizzing tab. Desperate, I quarantined all affected fish I could find to a 5g qt tank, and began treatment.
After 3 doses and following instructions, I altered the plan and started double dosing and dosing every day for 14 days straight. The worms appeared to disappear.
The fish were returned to the main tanks, and all was well for a little while. But, the worms returned. I had neglected to consider that perhaps treating on the visibly affected fish may not stop the invasion. So, I purchased 4 more packages of fizz tabs and began double dosing both tanks. The worms, were untouched this time.

Feeling nearly defeated, I scouted around, and someone recommended to me to try Metronidazole. Apparently an effective antibiotic and powerful antiparasitic, I made both some medicated food up, and began dosing the tank with a slightly above average dose size, following instructions, and coupled with the medicated food. I used 2 full vials and 8 full treatments, where apparently 2 are required at most. Still, the worms remained.

I began to get at my wits end now. It had been 10 months, and nothing I had tried had worked. Investigating the remaining meds on the market, I chose one of only 2 remaining medicines available to me. This was a commercial dog wormer that the Vetrinarian assured me would kill any cestodes and nematodes, and was surely “harmless to fish”. Harmless indeed, it killed 2 fish on the first dose.
A 65% water change removed it and it was returned to the vet, of course for a 100% refund. Unfortunately I cannot remember the particular brand, but it is one that claims to “kill all known types of intestinal worms, cestodes and nematodes”.

Well, my last remaining medicine available to me was Levamisole HCL in an injectable form. So I began hunting. Finally, after many months, I found a supplier near me, who claimed to be able to get the medicine.
I put in an order for a 12 oz bottle of the goat wormer.
Would arrive within 14 days I was told.
3 Weeks later I went into the store on my way by to enquire.
Levamisole HCL is no longer available within British Columbia due to some particular agent being “unsafe”.
So, I couldnt get it. What a bummer.
Knowing it was a last ditch effort, I started calling every Vetrinary Hospital and Clinic that is within driving distance.

Finally, on my 15th call, I found a Vetrinarian who dabbles in Fish Medicine. A breeder of Discus himself, he had encountered a particular nasty batch of Camallanus worms himself.
Through trial and error, he found a wormer that works.
This wormer is Fenbendazole.
So, he contacted an aquatic biologist friend, and they worked out a dosage.
Dissolve 3CC of powdered Fenbendazole in 100ml of water.
Mix well, then add as many bloodworms as you need to feed your fish. Soak for 30 mins to 1 hour, then dump the entire container in the tank, water and all.
So, for 14.35 in cost, I picked up my Fenbendazole in powder/crushed form.
The brand name it goes under is Panacur.
I brought it home, and prepared the first dose.
It seemed to really soak into the bloodworms, changing them to a slightly lighter and grayish color tone.
I fed the fish 2x A Day for 2 days.
I watched the affected fish carefully.
Within 36 hours, all worms have withered and dropped away from the affected fish.
Within 48 hours, I could find no remaining fish with Camallanus Worms protuding.
I followed up with a good gravel vac and a large water change.
I repeat this treatment in 2 weeks time, and then again in 2 weeks following if need be.
I have enough medication to do at least 7 more doses.
However, I dont think I will need it.

It looks like finally, almost 1 year after it began, the nightmare is over.
The fish and shrimp all responded well to the medication.
The discus adopted some slight stress coloration, but nothing drastic, and following the water change are back to their happy perky blue selves.
All in all, this wormer did a job well done.
It was fun and exhilarating to see the worms withering away within only a few hours of the first dose.

So, for all you frustrated and angered victims of the nightmare Camallanus, worry no more. Fenbendazole has come to the rescue.
By treating all new fish in QT with a 2day dose of medicated food, you now can avoid infesting your tanks with camallanus worms. Best of all…Fenbendazole also kills larvae and eggs.
So, in closing, I raise my head, and yell out a triumphant battle cry, armed with my bottle of Fenbendazole, and for the first time in a year, worm free fish.
They are eating better, the thin, emaciated ones are already starting to plump up after a week of being worm free. I see no signs of reinfestation, and while hesitant to think its truly over…I hold my breath and wait. The camallanus worm has a 30day life cycle…. stay tuned for a future update as to whether the worms reappear or stay gone. And Rejoice… may be 1 small step for worm fighting, but it is 1 giant leap in treatment options.

May you find your tanks too, healthy and worm free.
Best of luck.
TheGreatBlueDiscus – Koran Weston.