Lernaea sp. Phylum: Arthropoda
Class: Crustacea
Order: Siphonostomatoida
Family: Lernaeidae
Goldfish with an Anchorworm.
Anchorworm is actually a copepod (Crustacea) parasite. Lernaea cyprinacea is a species commonly found in aquarium fish although the family Lernaeidae contains other genera as well as other species. L. esocina is another species encountered. They are most frequently found on goldfish and koi although many species of fish can serve as suitable hosts. The name is often misspelled Lernea, Learnea, Learnia, and Lernia (this on a commercial therapeutic for the disease).
Anchorworm from Glossolepis incisus. Not fully developed. Click on photo for close-up.
Female Lernaea attach to and burrow into the skin of fish where they develop into what appears as a worm-like protrusion (actually the egg cases of the parasite) on the fish. Common attachment sites for the parasite are the base of the tail of the fish and the base of the dorsal fin, although they can be found on any fleshy part of the body. It is important to bear in mind that the initial attachment of the parasites often causes a swelling and redness of the site even when the organism is not visible. Such a wound on newly aquired aquarium fish may represent an imminent anchorworm infestation.
Lernaea larva, probably a day after hatching.
Diagnosis
Diagnosis of the disease is made by observance of the adult parasites which can be verified by viewing them under magnification. Observation of larval stages should not be used as sole basis for diagnosis since it it hard to distinguish them from those of non-parasitic copepods which are likely to be present in the water and on samples. Pathogenicity of the parasite depends on the numbers of parasites and degree of secondary invasion of wounds by bacteria and fungi. The goldfish shown in the picture at the top of this page survived with no treatment at all, and the lone parasite eventually disappeared although swelling and inflammation was present at the point of attachment for one week further. In aquaria the occurance of even one of these parasites is usually cause for some preventative treatment.
See page three for more photos of larval stages. Recently hatched nauplius of Lernaea.
Treatment:
The larval stage of Lernaea is susceptible to some of the same treatments used for protozoan parasites. Adults which have burrowed into a host fish are less vulnerable, but several medications (organophosphates such as used for skin or gill flukes) are effective in killing them. Dead parasites which remain on the fish may be a focus for further infection by bacteria and fungi and it is sometimes desireable (where feasible) to physically remove them with tweezers and/or disinfect the wounds. Concentrated Methylene blue works well for this purpose. It can be applied directly to the wound.
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