Anchor Worms (Lernaea)

This is a parasitic copepod that attacks mainly freshwater fishes, but have also been found in marine habitats. These parasites can be seen with the naked eye. Females are 10-12mm, males are 0.8mm.

Females are parasitic and embed themselves into the hosts flesh. They are held in place using a ‘holdfast’, where they begin feeding on the fishes’ flesh, organs and fluids. Reproductive potential is seen by the development of two egg sacs on the exterior/exposed part of the parasite, giving them that Y/T-shaped appearance. Young copepods are free swimmers, but soon attach themselves to the gills. Adults and eggs are introduced via live foods, infected water, or plants.

Symptoms: Fishes infected with these parasites can be seen ‘flashing’ on surfaces. This is the underside of the fishes as they attempt to rid themselves of these parasites. Other symptoms include localized redness, inflation of the body of the fish, breathing difficulties, lethargy, ulcers, dropsy, weight loss, loss of scales, gill and fin damage. Puncture wounds often introduce opportunistic, secondary infections.

Treatments: Infected individuals should be removed into a quarantine tank, as to prevent females from releasing their eggs into the main tank.
1) Salt has been recommended as the safest form of removal for effected fishes. 10-30 grams per litre.
2) Trichlorfon, Dipterex and Dylox (toxic to fishes and invertebrates – use with care)
3) Current treatments involves Dimilin

Anchor worms are actually crustaceans. The young are free swimming and borrow into the skin, go into the muscles and develop for several months before showing. They release eggs and die. The holes left behind are ugly and may become infected.

Treatment: The anchor worm is too deeply imbedded to safely remove. Treatment can best be done with a 10 to 30 minute bath in 10 mg per liter of potassium permanganate. Or treat the whole tank with 2 mg per liter, but this method is messy and dyes the water.