How to Treat Camallanus Red Worms in Aquarium Fish

Fish diseases can be notoriously hard to diagnose, but one of the more easily recognizable illnesses is an internal parasite called the camallanus red worm. Multiple species of roundworms and nematodes that belong to the Camallanus genus can infect aquarium fish. They attach to the intestinal walls, and they can co-exist for long periods of time with their host. However, added stress factors like bad water quality or tank aggression may weaken the immune system, allowing the worms to cause serious damage and even mortality.

Red Worms in Fish?

For a while, the fish will look quite normal in the beginning stages of the disease. Then you may start to notice that juvenile fish are growing more slowly than usual, the adults may not be breeding as much, and you are gradually losing a few fish here and there over the course of months. Some hobbyists also reported a loss in appetite.

If you see one or more red worms emerge from the fish’s vent, this is an indicator that it is serious. It can look like a cluster of little, scarlet threads sticking out about 1/4 to 1/2 inch (0.6-1.3 cm). At this point, the disease is at a very advanced stage where the fish may look abnormally thin (from the worms absorbing all the nutrients) or have a belly swollen with worms. Secondary infections can occur when worms block the intestines.

Camallanus worms can be more easily seen in small livebearers, such as guppies. It only takes a few larvae to cause serious damage in a tiny fish. It takes worms longer to reproduce to a size that can take down larger fish like angelfish.

Guppy with camallanus Worm protruding from anal vent

What causes Camallanus red Worms?

Infected fish can spread the parasites to their aquarium by eating the waste of the healthy fish. This is what causes the tiny crustaceans cyclops to eat the larvae. A healthy fish can eat infected crustaceans. This causes the larvae to mature and become adults, which allows the cycle to continue. Some species of camallanus worms do not need an intermediate host, and fish can get infected directly by nibbling on fish feces that contain larvae. Either way, the disease is fairly contagious, so adding plants, gravel, or equipment from an infected tank to a healthy tank can cause cross contamination that also spreads the parasite.

How can I get rid of Camallanus Worms

Treat the fish with a dewormer like Fritz Expel-P that contains levamisole and targets roundworms like camallanus. The medication paralyzes adult worms and allows them to be expelled by an aquarium siphon. Follow the manufacturer’s instructions on the box by using 1 packet of Expel-P per 10 gallons (38 L) of water. After 24 hours, perform a 25% water change to remove the excreted parasites. Because levamisole is not effective on unhatched eggs, it is best to wait for two weeks before you start the second treatment. Then, add Expel-P to the tank to eliminate any remaining parasites.

Fritz Expel-P medication for parasitic diseases

Some articles suggest that you put the dewormer into food and give it to your fish. However, we prefer to treat the entire tank as fish can lose their appetites and you can’t always control the amount of medication they eat. If your fish has secondary infections, you might consider broad-spectrum antibiotics and antifungal treatments.

Besides medication, the key to recovery is lowering stress in the aquarium or hospital tank. To help the worms get rid of their toxins faster and gain weight, feed them high-quality food. For paralyzed parasites to be removed, ensure that the water quality is high. You can also disinfect siphons, nets, and any other equipment that is shared to prevent the spread of disease.

Dosing an Expel-P packet

How can I prevent Camallanus Worms from getting my house flooded?

Before introducing new fish to your aquariums, we recommend that you quarantine them for a few days to observe their behavior, appetite, health, and general health. The trio of quarantine medications helps to prevent most bacterial, fungal and parasitic infections. However, if you are concerned about camallanusworms, Expel-P can be used as an additional treatment. Red worms can be tolerated by most fish for some time before becoming problematic. Keep the tank clean and provide fresh food. Keep the quarantine area separate, wash your hands after touching it, and use separate siphons and nets for fish in quarantine.

For more information on fish diseases, check out our collection of articles to learn how to identify, diagnose, and treat the most common illnesses.

Attributions 190629 Guppy 01 by BlueBreezeWiki. CC BY-SA 3.0