Lernaea Cyprinacea (Anchor Worms)

Lernaea cyprinacea

The parasite Lernaea cyprinacea, more commonly known as the anchor worm, can be harmful to your fish if left untreated. If you see your fish scratching at the surface of the water or if you notice white spots on the body, then it may have contracted this parasite.

Before treating your fish for this parasite, it’s important to know how to identify and treat it safely in order to avoid doing more harm than good.

Anchor worms are one of the most common external parasites on fish, although they can also be found in tropical areas around the world. They are easy to spot on larger fish such as Koi carp and Rainbow trout, but if you’re not careful, you might miss them on smaller fish like goldfish and ornamental koi.

There are a number of parasitic worms that affect freshwater fish, but one of the most common to affect koi and goldfish is the Lernaea cyprinacea, more commonly known as the anchor worm.

In this article, we’ll cover everything you need to know about Lernaea cyprinacea and how to treat it without risking your fish’s health.

What is Lernaea cyprinacea?

Lernaea cyprinacea

Lernaea cyprinacea is a parasite that occurs in freshwater fishes, primarily those from temperate regions. The term ‘anchor worm’ refers to their appearance when attached to the skin, where they are easily confused with cutaneous larva migrans or even a subcutaneous hornet or wasp sting. Anchor worms can cause significant damage if left untreated for too long.

Lernaea cyprinacea can infect many different species of fish and has spread rapidly throughout North America over the last several decades. The parasite itself is not harmful to humans but large populations can cause significant harm and sometimes death in their fish hosts.

The internal organs of infected fish become clogged with masses that may contain millions of parasites each. It is a very strong parasite because it causes extreme external deformities in its host, while also being a pain to remove at times due to its sheer number.

Another notable attribute about Lernaea cyprinacea is that they are hermaphroditic; upon reaching maturity some will change sex so that there are both male and female worms living on an individual host.

What do anchor worms look like?

Lernaea cyprinacea

They have a central, sac-like body that is red or brown in color and measures about 0.5 centimeters in length. Both male and female anchor worms grow their own ectopic limbs on surfaces of dead fish so they can catch their next host more easily.

Their exoskeleton ranges from greenish-white to tan and is covered by hair-like filaments called setae. Spines emerge from these tentacles along with several breathing pores which allow them to take oxygen directly from the air or even underwater.

Male Lernaea cyprinacea use modified setae as claspers during mating, allowing them to hold onto hosts until they’re ready for invasion. Female anchor worms lack these specialized claws; instead, they anchor themselves permanently onto hosts once they mate with an equally large male anchor worm.

Anchor worm life cycle

The adult female Lernaea cyprinacea will attach herself to a host fish and releases a hormone that prevents her from being removed. She begins to release eggs, which get picked up by water currents and hatch into free-swimming larvae. The larvae then attach themselves onto a host fish or salmonid as well, where they mature into an adult male or female within two weeks, completing the cycle.

Since both males and females look for another host for breeding, large numbers of nymphs can seriously hamper a fishery by reducing yields. This is also true if juvenile fish are involved; in fact, anchovies have been implicated in high levels of mortality in juvenile pink salmon stocks along with Alewives.

Removing infected fish is especially important during outbreak years when many larvae are present on the river’s bottom waiting for fish hosts to pick them up. If your body comes in contact with a single parasite larva, it can cause skin irritation around the location of exposure.

If a large number of larvae are introduced into your body via raw or undercooked seafood, it could lead to a systemic infection known as visceral larval migrans (VLM). Symptoms include fever, nausea, gastrointestinal distress, and vomiting at first followed by lethargy and weight loss due to malabsorption of nutrients.

Anchor worms on fish

Lernaea cyprinacea

Lernaea cyprinacea is a type of copepod and a parasite that afflicts aquarium fish. Fish most commonly affected are barbs, Danios, tetras, killifish, and gouramis. It is also known as a fish louse. Lernaea begins its life as a tiny crustacean larva that swims towards potential hosts, especially weakened or stressed ones in an aquarium environment.

The larvae will attach themselves to a host’s body, sink their sharp mouthparts into it and feed on skin tissue. They remain anchored by means of hooks at their rear end that resemble thorns; hence one common name for them, thorny-headed worms. As they feed, they grow larger and molt twice before reaching maturity. Most species have only three molts before reaching maturity but some go through five or six molts.

Lernaea cyprinacea is a type of parasitic copepod. Once infected with an Anchor worm, fish will develop unsightly spots from its skin and flesh, which can cause ulceration of scales and fins.  The affected fish may appear lethargic and atrophied. Other signs include difficulty swimming, pale coloration, and anorexia; however, these are not always present in severe cases.

What causes anchor worms on fish?

The main culprits behind Anchor worm infection are poor water quality and infested carriers. Water that has been contaminated by other aquatic creatures such as birds, turtles, or even humans, contributes greatly to infestation.

Poor handling practices when moving fish between aquariums or ponds can spread diseases quickly among tanks.

Fish hosts such as small Koi, guppies, and some types of frogs that naturally carry parasites are common sources for disease transmission.

Anchor worm on goldfish

It’s more common than you think! Did your fish turn belly up, float at its side, or spend a lot of time hanging out on its side? Does it has sores around its gills? Has your goldfish’s swimming pattern changed?

If you answered yes to any of these questions, there is a good chance that your goldfish has been infested with Lernaea cyprinacea. Fortunately, it is very easy to treat. All you need are basic aquarium tools and some patience! You will want to first use tweezers or forceps to get rid of as many parasites as possible.

Anchor worm in humans

In rare cases, an infection of Lernaea cyprinacea may occur in humans. Humans can become infected by eating raw fish or shellfish that contain encysted larvae, which are able to penetrate human skin. Once under a human’s skin, they emerge as adults, mate, and reproduce within their new host.

In adult form, Lernaea cyprinacea usually attach themselves to a person’s eyelids using sharp pincers; not only do these infections cause itchiness and irritation, but eye damage is also possible.

How do I remove Lernaea cyprinacea?

When it comes to treatment, anthelmintic medications like levamisole and praziquantel can help remove Lernaea cyprinacea from your body, but they do not kill any of your fish. The most effective treatments for fish are heat and dilution, as they will kill both larval and adult forms of Lernaea cyprinacea – but only when used correctly. By no means should you use them together, however, be sure to follow one method for several days before moving on to another.

One common way of removing Lernaea cyprinacea is through a skin scrape. Your veterinarian will use a scalpel to remove them from your fish’s body. To ensure that none of them remain, he or she will then disinfect and clean your fish’s wounds. There are also products available for home treatment of parasites such as these; simply consult with a professional before purchasing.

Once they have been removed, it may take some time for any wounds to heal; making sure to keep your fish in optimal water conditions will help reduce stress during this time. If there are any open sores that aren’t healing, consult with a professional immediately as they could become infected quickly if not tended properly.

Anchor worm treatment

Lernaea cyprinacea

If your fish have anchor worms, an easy way to treat them is with a salt bath. You can either add about 1 teaspoon of sea salt for every 4 liters of water or make a 50 percent solution. If you’re using table salt, it may be beneficial to make a weaker solution because table salt tends to be made from desalinated water.

The salinity should match that of seawater; if your tap water is hard and close to seawater salinity, then you shouldn’t need to adjust it at all. Use warm but not hot water, too hot temperatures will damage your pet’s skin, and leave them in there for about 15 minutes once or twice a day until he looks better. Clean any rocks or decorations in the tank while you’re at it. Keep up treatment for about a week after all signs of infection disappear, just to be sure.

It might take longer than that, however, Lernaea cyprinacea live under the scales so when they die and are expelled from their host fish during cleaning or treatment, they go unnoticed. When conditions are right, temperature, food availability, and so on, they can revive quickly and become infective again within two weeks!

How do you treat anchor worms naturally?

If your fish are infected with anchor worms, there are several options available to treat them. The two most effective treatments, in our experience, are either freshwater marbles or garlic oil. Either of these natural treatments is typically enough to wipe out a mild infestation. Of course, we don’t recommend these at all if you have goldfish or koi because they can swallow them. But for smaller tropical fish, it’s a good way to go.

Once applied, these products quickly kill off any remaining larva and prevent any new anchor worm eggs from hatching. There are many other kinds of treatment as well such as salt baths and formalin baths, but none that we find work as effectively. Marbles and garlic oil usually solve problems within 2-3 days whereas formalin baths often take weeks to complete before you see results.