Overview
This article discusses my personal experience with the identification and treatment of camallanus worms in aquariums. Dealing with this insidious pest has been one of the most aggravating, yet ultimately, most rewarding experiences in my 15+ years of fish keeping. Currently I have two tanks, one 34 gallon planted tank which currently houses a few varieties of common Dwarf South American Cichlids, the other a 10 gallon tank which houses two otocinclus and one juvenile L046.

A few months ago I had two fish die over a short span in my 34 gallon planted tank. I did the usual as I do after any death: check the water, look for anything out of the ordinary, and do a large water change. I noticed that one of the fish that died - a Golden Dwarf Nannacara) had two tiny short-red fibrous bristles protruding from his vent. When I examined the remaining fish a few days later I noticed my male Apistogramma MacMasterii had these same red bristles protruding from his vent. However, when I looked at him later that very day these bristles were hardly noticeable. I had little concern about this at first since he appeared to eat well and act normal. Two weeks later this fish had stopped eating and did little more than merely stay alive. About this same time I noticed the symptoms appear on the female MacMasterii and my male Bolivian Ram. It finally clicked that my fish must have some parasite. After looking online for an afternoon I realized what the problem was…camallanus worms. In one forum these symptoms were referred to as “bristle butt” [1]. I would modify that to “red bristle butt”, namely if your fish has little red bristles sticking out from its vent it is infected with camallanus and, unfortunately, probably all of your fish are infected as well.

The reason I’m not using the scientific name of the camallanus is that I am not sure which type commonly infects aquarium fish. Just do a GoogleTM search and scroll through the results and you will most likely see the following names: Camallanus Anabantis, Camallanus Cotti, Camallanus Lacustris, Camallanus Oxycephalus, and perhaps many others. In these results it often states “common parasite in aquatic fish.” I suspect that aquarists deal with Camallanus Cotti, but this does not seem easily verifiable.

Parasite Lifecycle
The life cycle of the camallanus is a complicated thing. One website said that it originated from Japan but has since spread all over the world [2]. The camallanus can have a direct or indirect parasitic cycle. Meaning the infection can spread from fish to fish or from fish to an intermediate host to another fish. This implicates that letting a tank lay fallow of fish will not stop this pest. The camallanus has a five stage lifecycle. From what I can understand the life cycle is defined by the number of molts this particular type of worm goes through. The first stage consists of a new-born, free swimming larva. An intermediate host such as a copepod or the direct host - in an aquarist’s case this is the fish) then ingests this larva. For the indirect cycle, the fish consumes the infected copepod and contracts the parasite. In the direct host the camallanus molts twice over the next ten days, then twice again before reaching full maturity at 30-40 days. The female camallanus hangs f rom the anus of the infected fish, sheds microscopic eggs, and thoroughly infects the entire tank - lucky for us!) [3].

Treatment Options
After pouring over literally hundreds of articles pertaining to treating this dreaded parasite I formed the list of possible treatments. Here is a summary of treatment options that I found and, as best I could tell, the appropriate doses.

Ivermectin 1% solution
Recommend Doses:
Option - 1): 0.3mL/100 L
Option - 2): Treatment over 4 days, per 76L Day 1: 0.1 mL Days 2 -4: 0.2 mL

According to different articles Ivermectin is probably the most effective broad-spectrum anthelmintic - anti-parasite) drug to date. It is commonly used on a variety of different farms animals and, therefore, just about every feed/farming store carries it. Ivermectin works by targeting particular synapses in the central nervous system. It is minimally toxic to mammals since the blood-brain barrier protects the central nervous system [4]. Apparently Ivermectin is commonly used to medicate fish in commercial farms, however the error margin for overdosing with fish is very small and there is still debate over the toxicity of Ivermectin to fish [5].

Piperazine
Piperazine citrate is the most common anthelmintic form of the drug. One interesting fact I discovered is that Piperazine is in the same class of drugs as Viagra [6]. The dilemma with Piperazine is that in order for it to work best it must the infected fish must ingest it. Personally, I find it ridiculous when fish medications say “get the fish to eat this”. I don’t think I have ever had a sick fish eat, ever. The recommended dose that I saw for this was adding 25 mg per 10 grams of food [7]. If the whole, trying-to-get-your-sick-fish-to-actually-eat-nasty-tasting-medicine-route was not discouraging enough, piperazine comes in non-water-soluble tin oxide base filler. Adding this to the tank will obviously cause a huge mess and, furthermore, the tin oxide is believed to be detrimental to plants [8].

Fenbendazole
Fenbendazole is another anthelmintic medication. This often goes under the name of PanacurTM or Safe-GuardTM. I have personally used Panacur TM to treat pinworm infections in tortoises. Some people have also had great success treating camallanus with Fenbendazole; however it seems most effective when ingested. Some folks claim that Fenbendazole causes less stress on fish than another common anthelmintic, Levamisole. There is a write-up about the successful use of Fenbendazole to treat camallanus on PetFish.net [9], but the dosing rate discussed is very ambiguous. One veterinarian site suggests adding 2mg per liter - mg/L) of tank water once a day for seven days [10]. Another suggested medicating orally at 11mg per kilogram of fish bodyweight per day for three to five days [11]. Most of the dosing recommendations I saw were based on the weight of the fish or as a percentage of feed. I personally think this is problematic because I’d have trouble estimating how many kilograms my bite- sized half-dollar sized fish weigh. As for adding to the feed, I would say the average dose I saw was anywhere from 0.1 to 0.25% of feed given for three days then repeated in two to three weeks [12].

Metronidazole and Praziquantel
Metronidazole and Praziquantel are common parasiticides sold in most local fish stores. Aquarium Pharmaceuticals makes a product called “General Cure Anti-Parasitic Fish Medication” which contains both of these medications. Unfortunately these medicines are best used for exterior parasites [13], and are not effective against camallanus. I know this first hand because I tried this as a “shot in the dark” while I waited for another medication I ordered to arrive. After faithfully following the suggested two doses my infected fish showed no change in their condition.

Levamisole
Levamisole is another broad-spectrum anthelmintic. The general consensus is that Levamisole is generally well tolerated by fish. After all my reading I am still not clear exactly how it works other than it either kills internal parasites which allows the fish to expelled them [14]. Levamisole is often used in humans for the treatment of colon cancer [15] which could explain why it can be tricky to get in different places. I have read of Levamisole doses for camallanus ranging from 1mg/L to 30mg/L. The vet that responded to a thread on forums.loaches.com suggested a single dose of 2mg/L for 24 hours followed by a massive water change. Another veterinarian website suggested a 1mg/L-2mg/L dose for 24 hours [9]. Apparently this dosing regime came from The Exotic Animal Formulary, 3rd Edition by James W. Carpenter.

My Experience
Based on the information I had and the drugs I seemed to have potential access to, I choose to go with Levamisole Hydrochloride. I went through an online farm supply store, www.valleyvet.com, to purchase it since Levamisole is also common de-worming medication used on swine and sheep. There are a lot of misconceptions about the stability of this drug in water. I spoke with the veterinarians at Valley Vet to ascertain the facts. Levamisole, by itself is not easily soluble in water and indeed not stable once dissolved in water with a Ph greater than 7.0. Meaning, it will break down and be rendered ineffective. Levamisole with a base, such as Levamisole Hydrochloride or Levamisole Phosphate, which are both easily water soluble, are stable in water for approximately 90 days. This explanation was also corroborated by another vet in one of the most comprehensive – and very informative – write-ups on this topic at forums.loaches.com [16].

I ultimately went on a hunch that Levamisole is pretty safe and since I saw dosing recommendations ranging from 1mg/L all the way up to 30mg/L, I opted to go with 25mg/L for pretty much no apparent reason. I first dosed my planted tank. I wanted to ensure this was safe before dosing the zebra tank. Nothing in the zebra tank showed any signs of infection but I just wanted to treat it as a precautionary measure.

After dosing the planted tank the fish were expelling some of the worms within the first hour. The Dwarf South American Cichlids in the tank did get lethargic and seemed to labor with breathing. All of the invertebrates also stopped moving and were clearly unhappy about the treatment. However the standard issued plecostomus and the mutt-catfish seemed completely oblivious to the medication in the tank. I let the treatment go on for 24 hours. At that time there were no deaths of fish or inverts. I proceeded with a 50% water change, added Marineland Black Diamond charcoal to the filter, then went on to medicate the zebra tank.

When I medicated the zebra tank I observed a similar response by the inverts: major lethargy. After 24 hours I performed a 50% water change and added carbon to the filter. The otos and zebra never showed effects of the medicine and seemed as perky and intent on hiding as usual! In this tank I only lost one of approximately ten little Red Cherry Shrimp in the whole process.

The next day I checked on the planted tank and noticed the female MacMasterii still had two worms still in her vent. Seeing that patience is not one of my virtues I decided to medicate the tank again, this time at a level of 30mg/L. Almost immediately the lethargy set in on all the Dwarf South American Cichlids and inverts. Yet again the catfish and pleco seemed unaffected. The level of this dose was probably nearing the lethal threshold for some of the fish because over 24 hours some of the fish hardly moved. I did a 70% water change and vacuumed the substrate as best as one could in a planted tank. After the dust settled I cleaned out my Eheim 2026 filter and added carbon. In this process I lost one of approximately eight Amano shrimp.

Twenty-four hours after the treatment I saw the male MacMasterii out swimming. This was a huge surprise as I honestly thought he died since I had not seen him in six to eight weeks. He had three worms still hanging from his vent but they were hanging out further than I’d seen in any fish and I figured he was passing them. The female was out as well and had worms hanging in a similar fashion. The male Bolivian ram no longer had any sign of worms from his vent. The catfish and pleco still seemed oblivious to the treatment.

Forty-Eight hours after the treatment the male and female MacMasterii both came out from hiding when I approached the tank. Then something miraculous happened, I fed them…and both of them ate sparingly. Later that evening I noticed that the “Terrible two” MacMasterii were out and bossing the rams around in full force! Just seeing that the medication helped them so much, and seeing such a dramatic improvement proved one of the most rewarding experiences I have ever had in fish keeping.

Almost two weeks later all of the fish seemed free of worms, they ate, and seemed quite well overall. The female MacMasterii still seemed a little slower than usual but she was probably the most infected fish in the tank. As a last paranoid precaution I medicated the tank again, this time at 12.5mg/L. Even at the lower dose the fish seemed lethargic, the inverts inactive, and the pleco and catfish unaware that anything differed from usual.

At the time I’m writing this, it has been approximately three weeks since the first treatment with Levamisole HCl. All of my fish are doing wonderfully, and other than the loss of two shrimp, all the inverts are back to normal behavior. Although only time will tell, right now none of my fish have signs of camallanus and by all observable means seem amazingly well compared to their sickly state just a few weeks ago.

Although I have no conclusive proof that various catfish species are particularly susceptible to camallanus worms, treating catfish with Levamisole HCl had very little, if any, outwardly apparent negative effect. If camallanus is suspected in catfish species I would suggest dosing Levamisole HCl at 30mg/L for 24 hours followed by a 75% water change and removal of the remaining medication by adding carbon in the filtration. Because of the adverse reaction I noticed in my Dwarf South American Cichlids, for other types of fishes I would recommend dosing Levamisole HCl at 20mg/L for 24 hours, followed by a 75% water change and removal of the remaining medication by adding carbon in the filtration. If you are over paranoid like me, I would suggest repeating this treatment for both cases - 1) if worms are still visible after 48 hours or - 2) regardless in ten to fourteen days just to ensure all worms in the tank have been killed. I am not saying this is what a veterinarian would recommend, but this is what I did and camallanus worms are now a thing of the past - keep fingers crossed)! Lastly….a good preventative option: There is an anti-parasite medicated food made by Jungle Labs that has Levamisole - 0.4%, Praziquantel - 0.5%, and Metronidazole -1% as active ingredients. I am not sure how well it works on sick fish – as I mentioned I’ve never had sick fish that eat, but I’ve planned to start feeding my healthy fish this for three consecutive days every week for a month each time anything new goes into that particular tank. This just might be the “ounce of prevention” - or “28.35 grams of prevention” – for all the metric folks) that could keep camallanus and other nightmarish-parasites at bay!

References
[1] The Fishroom Library Archives, “Camallanus Alert”, 03/12/2007.
[2] Berland, Bjorn, “Musings on nematode parasites”, November 2006.
[3] The Krib, “Nematode Infestations”, 03/12/2007.
[4] Wikipedia The Free Encyclopedia, “Ivermectin”, 03/12/2007.
[5] An excerpt about Ivermectin and Fish, 03/12/2007.
[6] Wikipedia The Free Encyclopedia, “Piperazine”, 03/12/2007.
[7] Tuskegee Website – Pathobiology, “Chapter 12 Biology of the Common Diseases of Fish” , 03/12/2007.
[8] Angelfish Form, Aquaira Web Forums, “PARASITES The worst kind CAMALLANUS”, 03/12/2007.
[9] Petfish.net Online Aquarist Community, “Camallanus Worms: An Aquarists Worst Nightmare”, 03/12/2007.
[10] Veterinary Services, “Fish Updated 08/26/2003” – 03/12/2007.
[11] Francis-Floyd, Ruth, University of Florida, “Incorporating Pet Fish IntoYour Small Animal Practice”, 03/12/2007.
[12] Tappin, Adrian R., “Worm Infestations”, February 2007.
[13] Goldfish & Aquarium Board - GAB), “Medicated Food Explained and Explored”, 03/12/2007.
[14] Wikipedia The Free Encyclopedia, “Anthelmintic”, 03/12/2007.
[15] MayoClinic Tools for Healthier Lives, Drugs & Supplements, “Levamisole - Systemic)”, 03/12/2007
[16] Loaches Online Forums, “Levamisole”, 03/12/2007.

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