Contrary to its name, the Anchor Worm not a worm. Instead, it is a parasitic crustacean commonly found in freshly purchased fishes. These are common parasites of ornamental fishes, such as goldfish and koi, but can easily infect any kind of species, including trout, catfish and many others. Heavy infestations of anchor worm could severely affect the host fish, making it vulnerable to other fungal and bacterial infections. A single anchor worm can immediately kill a small fish. Sometimes, the anchor could penetrate the fish’s skull or cavity, causing a more rapid death.

Diagnosis of anchor worm infestation is based simply on the identification of parasites attached to the fish.

A veterinarian can remove of anchor worms on a single fish using light sedation. Anchor worms can also be treated with a solution of potassium permanganate. However, to eliminate several parasites and treat heavy infestations, other chemical treatments like antibiotic therapy, chitin inhibitors and organophosphate insecticides may be necessary.

The most noticeable symptom of a fish with anchor worm is the whitish-green threads that hang out of the its skin with a red and inflamed area right at the point of attachment. Most fishes with anchor worms scrape itself against different objects.