The Camallanus Worms are one of the most commonly found internal parasites that infect fish ranging from just aquarium fish to even fish that are inside of a pond. Many may think that the fish that is infected is pregnant or giving birth to either live fry or eggs due to the way that their anus may appear when infected. Sadly, due to the way that this parasite infects its host fish and lack of understanding, the fish can not only become very ill but if not treated the parasite can prove to be fatal to the infected fish.
The most common identification of this worm infecting a fish is the presence of red thread-like worms that are hanging out of the fish's anus. The other symptoms that the fish can display include bloating of the stomach area, dull coloration of the fish, staying in one area of the tank, and being lethargic. Some species can show no symptoms of infected besides the worm hanging from the anus, while others may show all visible signs of infection depending on the conditions of the water that they are in.
In order to understand how to treat and remove the camallanus worm completely, we must first understand how the camallanus worms lives and reproduces. The camallanus worms must go through three different stages before it is able to infect fish that are within its water column. We will start with the free living stage (it's first stage) in order to provide a better understanding. The larvae will settle out onto the bottom of the substrate where they will start to wiggle around and try to prove as food to crustaceans. Once eaten by a crustacean, they will stay within the infected crustacean while they grow and mature into their next stage. Within a timeframe of about a week they will start to molt multiple times and become slightly dormant waiting for a fish to eat the crustacean. If the crustacean is never eaten and dies due to its natural lifespan ending, the final stage will never take place and the dormant camallanus worm will die due to a lack of food from a host. However, if the crustacean is eaten than the camallanus worm will become active again as it passes through the internal organs of the fish. The familiar red worm that is near the anus of the fish is an active, sexually mature male or female trying to find another infected fish in which the worm can mate with and produce the larvae all over again. If the worm is able to find another worm that is of opposite sex, the larvae will be producing and attach to the fish's waste in order to repeat the life cycle all over again.
Treatment and Medications
Since this worm is the most common parasite that can infect fish, it has multiple different types of treatments that are known to work and kill off the parasite in different manners. The first set are fenbendazole, levamisole, and praziquantel which instead of killing the parasite off will just paralyze them making them unable to mate or stay attached to the fish and become pushed out by the fish's waste. Within 24 hours the substrate should be thoroughly cleaned and rinsed of using any of these medications to prevent the worms infecting the fish again.
Antihelminthic medications are highly toxic to both snails and shrimp, and the must be removed before treating to prevent having deaths of them. This medicine is also toxic to fish if used incorrectly such as at a higher dosage rate then stated on the bottle, but is highly effective at killing the parasite off. This is the most common medicine to be used when treating any type of delicate fish that is infected since it has such as high rate of success when used in treating the whole water column that is infected. If you treat only the given infected fish inside of a quarantine tank, other fish may already be infected and not show signs in the main tank where the fish was found to be infected at.
Due to the way that this disease effects the inhabitants, the best prevention methods are to always make sure that you quarantine anything that you place inside of your water (this includes any plants, inhabitants, decorations, and more). Thus, when you do let them adjust to your water and you truly see how they are acting, eating and if they have any symptoms or signs, we will either start to get a better understanding if they are infected, or learn about what possible other diseases they might have.