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 feed by attaching themselves to the intestinal walls. The immune system may be affected by factors such as tank aggression or poor water quality, which can lead to serious injury and even death.

Red Worms in Fish?

The fish may look normal for a time in the initial stages of the disease. In the later stages of the disease, your fish may look normal for a while. However, it is possible that your fish start to change. Your fish may be growing slower than usual and the adults may not be reproducing as well. You might also notice that you are losing fish slowly over time. 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 may look like a small cluster of scarlet threads that extend about 1/4 to 1/2 inch (6.6-3.3 cm). This stage of the disease can cause fish to become abnormally thin due to worms eating all their nutrients. Secondary infections can develop from worms blocking the intestinal tract.

Camallanus redworms are more visible in small livebearers such as guppies, because it takes only a few of them to cause serious problems for a nano fish. It takes worms longer to reproduce to a size that can take down larger fish like angelfish.

Guppy with camallanusworm protruding out of the anal vent

What causes Camallanus red Worms?

If infected fish are introduced to your aquarium, the sick fish passes out the worm larvae in its waste, which are eaten by tiny crustaceans like cyclops. Healthy fish will eat the infected crustaceans. The larvae become adults and can reproduce in the fish’s body. 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. Cross contamination can also occur when plants, gravel, and equipment are added to infected tanks.

How do I get rid Camallanus Worms

Treat the fish with a dewormer like Fritz Expel-P that contains levamisole and targets roundworms like camallanus. The medication paralyzes the adult worms, allowing them to be removed from the fish via an aquarium siphon. Follow the instructions on the package and use 1 packet Expel-P for every 10 gallons (38 liters) of water. Perform a 25% water changing to get rid of the parasites after 24 hours. Since levamisole does not affect unhatched eggs, wait two weeks after the initial treatment and then dose the tank again with Expel-P to deal with any remaining worms.

Fritz Expel – medication for parasitic conditions

Some articles suggest putting the dewormer inside food and giving it to the fish. We prefer to treat the entire tank, as sometimes fish lose appetites and you don’t have control over how much medication each fish consumes. You can also use broad-spectrum antifungal or antibiotics if you fish have secondary infections.

The key to recovery is not medication. It’s about lowering stress levels in the aquarium and hospital tanks. 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 Expel-P in a package

How do I prevent Camallanus Worms

We recommend quarantining all new fish for a few weeks to observe their behavior, appetite, and overall health before adding them to your display tanks and potentially infecting your existing animals. Preventative treatment with the quarantine medication trio helps ward off most bacterial, fungal, and parasitic infections, but if you are worried specifically about camallanus worms, consider adding Expel-P as a separate treatment regimen afterwards. Redworms are not a problem for most fish. However, it can cause problems in some species. Make sure to keep the tank clean, provide fresh water and reduce stress. Finally, avoid cross contamination by keeping the quarantine tank in a separate area, washing your hands thoroughly after touching the quarantine tank, and using separate nets and siphons 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 190729 Guppy 01 by BlueBreezeWiki (CC BY-SA 3.0)