You don't need a microscope to see Anchor Worm. The adult female which is the only one you'll find on your koi or pond fish (males die shortly after mating) looks like a thread hanging from your fish with a pair of egg sacs that are shaped like a "Y" at the end on the body. The head (which has anchors) of the Anchor Worm is imbedded into the body of the goldfish. The piercing of the skin causes inflammation. However, the biggest threat is, the bacteria infection anchor worm causes leaving a hole in the protective "slime coat" and skin. These "holes" give the opportunistic bacteria such as Aeromonas or Pseudomonas which are one of the biggest causes of deadly ulcers (body sores) to invade your koi and pond fish. Anchor worm can survive winter conditions as an adult female on your koi or as eggs.
Goldfish with fish anchor worm will itch "Flash" rubbing against the sides, bottom and the rocks of your goldfish aquarium. Plus, you'll see an increase in the "slime coat". Some goldfish may become inactive and show increased gill movements (heavy breathing).
Attached anchor worm can be removed with tweezers as long as the goldfish can be caught without must stress. Care must be taken to remove all parts of the parasite. Once the anchor worm are removed the area should be treated with hydrogen peroxide on a Q-Tip.
Anchor worm should be treated the same as Fish Lice. Two of the best products on the market that treat Anchor Worm and Fish Lice are Anchors Away by Jungle and Dimlin. Just follow the directions on the label. If your goldfish show signs of ulcers treat immediately with Medi Gold.