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. There are multiple species of nematodes or roundworms that are part of the Camallanus genus that can infect aquarium fish. They attach to the intestinal walls, and they can co-exist for long periods of time with their host. 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.

Does My Fish Have Red Worms?

In the early stages of the disease, the fish looks quite normal for a while. You may notice that the juvenile fish grow slower than normal, the adults are not breeding as often, and eventually, you will lose a few fish every month. 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). This stage of the disease can cause fish to become abnormally thin due to worms eating all their nutrients. Because the worms are blocking the intestines, secondary infections can take root and cause other symptoms to appear.

Camallanus red worms are often more noticeable in small livebearers like guppies because it only takes a few worms to cause serious problems in a nano fish. It takes worms longer to reproduce to a size that can take down larger fish like angelfish.

Guppy with camallanus worm protruding from the anal vent

What Causes Camallanus Red Worms?

Infected fish can be introduced to an aquarium and the larvae of worms are passed on to the fish. These larvae are then eaten by small crustaceans such as cyclops. Healthy fish will eat the infected crustaceans. The larvae become adults and can reproduce in the fish’s body. Some species of camallanusworms don’t require an intermediate host. Fish can also get infected by eating larvae-rich fish feces. The disease can be spread from one tank to another.

How Do 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 works by paralyzing the adult worms so they can be expelled from the fish and removed via an aquarium siphon. Follow the instructions on the package and use 1 packet Expel-P for every 10 gallons (38 liters) of water. After 24 hours, perform a 25% water change to remove the excreted parasites. Wait two weeks to treat unhatched eggs with levamisole. After that, you can then add Expel P to your tank.

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. Also, if your fish has secondary infections that need to be addressed, consider using broad-spectrum antibiotics or antifungal treatments as needed.

Besides medication, the key to recovery is lowering stress in the aquarium or hospital tank. Feed plenty of high-quality foods to help them gain weight and expel the worms more quickly. Keep the water quality high and vacuum the substrate more frequently to remove any paralyzed parasites. Also, consider disinfecting any nets, siphons, and other shared equipment to stop the spread of disease.

Dosing a packet of Expel-P

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. 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 190729 Guppy 1 by BlueBreezeWiki. (CC BY -SA 3.0).