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. Aquarium fish can be infected by a variety of nematodes and roundworms. They attach to the intestinal walls, and they can co-exist for long periods of time with their host. However, additional stress factors such as poor water quality and aggression from tanks can weaken the immune system. This could lead to serious damage or even death.

Is my fish a victim to red worms?

For a while, the fish will look quite normal in the beginning 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 can look like a cluster of little, scarlet threads sticking out about 1/4 to 1/2 inch (0.6-1.3 cm). The disease has reached a very advanced stage and the fish might appear abnormally thin or swollen from the worms. Secondary infections can occur when worms block the intestines.

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. The worms need a much longer time to multiply to a point where the population that is large enough to take down bigger fish like angelfish.

Guppy with camallanus worm protruding from 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. When a healthy fish eats the infected crustaceans, it becomes contaminated and the larvae mature in the fish’s body into adults that can reproduce, thus continuing the cycle. 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 of Camallanus Worms?

Fritz Expel-P, which contains levamisole and targets roundworms such as camallanus, can be used to treat the fish. 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-P medication for parasitic diseases

Some articles recommend putting the dewormer in food and feeding it to the fish, but we like to treat the water of the whole tank because sometimes fish lose their appetites and you cannot always control how much medication each fish eats. If your fish has secondary infections, you might consider broad-spectrum antibiotics and antifungal treatments.

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. Keep the water quality high and vacuum the substrate more frequently to remove any paralyzed parasites. To stop disease spread, disinfect any siphons and nets.

Dosing Expel-P in a package

How Do I Prevent Camallanus Worms?

All new fish should be quarantined for at least a week to monitor their behavior and appetite before being added to your tanks. This will allow you to avoid infecting any of your animals. While the trio of antibiotics can prevent most infections (bacterial, fungal, or parasitic), you should consider using Expel-P to treat specific concerns. Most fish can survive with red worms for a while before it becomes problematic, so keep clean water, feed fresh foods, and endeavor to lower the stress in the tank. Keep the quarantine area separate, wash your hands after touching it, and use separate siphons and nets for fish in quarantine.

Check out our articles for more information about fish diseases. Learn how to diagnose, treat, and prevent the most common ailments.

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