Anchor Worm
Lernaea
Moderate severity ⚠️ Contagious
A visible crustacean parasite that embeds in the skin, leaving a thread-like tail.
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Symptoms
Whitish-green threads hanging from the body, red inflamed attachment points, rubbing and flashing.
Causes
A parasitic copepod usually introduced with new fish or pond plants and live food.
Treatment
Remove visible worms with tweezers and dab the wound with antiseptic, then treat the tank with an anti-parasitic (diflubenzuron) to kill larvae over several weeks.
Prevention
Quarantine new fish and pond plants; inspect arrivals carefully.
FAQ
Can I just pull anchor worms off?
You can remove visible adults, but you must also treat the water to kill the larval stages, or they return.
Where do anchor worms come from?
Almost always from new pond fish, plants or live food. Quarantine prevents most outbreaks.
This information is general guidance, not veterinary advice. Consult an aquatic vet for serious cases.