Pond fish get anchor worms. It's a fact. Your Koi do not need to be ill, or stressed to be infected with Anchor Worms.

Anchor Worm eggs can take up to 15 days to hatch. Juvenile Anchor Worms are microscopic. If pond fish are hosting juvenile anchor worms you will notice 'flashing' or 'rubbing' activities on your fish. They are trying to rid themselves of the nasty little parasites that have attached and are hanging on for a ride.

If you can see a tiny threadlike organism stuck to your pet then you are seeing the adult female Anchor Worm (males die after mating). Her head is hooked to your fish and is making a red spot or sore at the point of attachment. She has burrowed through the slime coat and dug her 'anchors' into the body of your fish!  The split tail is actually egg sacs ready to release 100s of Anchor Worm eggs into the pond environment.