Gill Flukes

Extremely common in both koi and goldfish, gill flukes can be the most destructive of all parasites known to freshwater fish.

How to Recognize, Treat and Prevent Gill Flukes in Your Koi or Goldfish Pond

You won't see them without a microscope but the fish know they are there!  They wiggle around and gather in groups at the openings of the gills and feed off the tender tissue.  Left unchecked flukes can cause bacterial gill disease and make it almost impossible for your fish to process oxygen through the gills.  They actually carry bad bacteria around with them and, after they've drilled holes into the skin of your fish they leave bad bacteria behind to boot.  This turns into ulcer disease.  Flukes are probably the deadliest of all the parasites because they leave so much destruction behind.

Recognizing Flukes

You must look through a microscope if you want to see gill flukes.  If they weren't so deadly they would be entertaining slithering around like tiny slinky toys with funny-looking Medusa heads.  If you don't have a microscope there are some clues to know (or at least suspect) that your koi or goldfish have gill flukes. 

Like all the other parasites, flukes tickle the fish so the fish will scratch themselves against the bottom and sides of the pond.  Gill flukes, however, attack the gills while other parasites are less selective so flukes may cause more problems with the fish being able to process dissolved oxygen in the water.  Head hanging and gasping for air along with the flashing (scratching themselves) may indicate the presence of flukes because the fish are obviously not getting enough oxygen.      

Treating Flukes

Flukes multiply like rabbits so it's very important that two treatments are done about 4 to 7 days apart - whatever the package directions say.  This kills the babies that are born after the adults are killed.  We suggest using Prazi Pond, Fluke Tabs or Anti-Fluke.  Prazi Pond is best to use if it's cold when treating because it works in lower temperatures though it also works fine during summer.  An added benefit to Prazi Pond is that it also treats internal parasites.  Fluke Tabs are easier to use for quarantine tanks because each tab treats 100 gallons.  Anti-Fluke (which is part of our parasite pak) is best used in warmer weather.

Salt will do nothing for flukes.  It doesn't hurt, however, to perform a salt treatment along with any of the treatments described above because it will encourage the fish's natural protective slime layer to form and it won't have any interactions with the medications.

You will need to have de-chlorinator on hand (if you use chlorinated water) because some water changes will be necessary.

Emergency Procedures

1. Treat the whole pond with either Prazi Pond, Anti-Fluke or Fluke Tabs.
2. For added benefits, perform a salt treatment while treating for anchor worm.

What to Expect Next

Gill flukes are responsible for many secondary infections.  You can almost expect ulcers to come up and there may be serious gill damage on surviving fish.  Once the flukes are killed the next two weeks are critical.  It would be advisable to keep the salt in there until the danger has passed and you might even treat the pond with a bacterial treatment, especially if you see any infection such as ulcers manifesting.  If you treat with FuBa Fix after the Gill Fluke treatments not only will you be treating the bacterial portion of the secondary problems you will be heading off any fungus that might eat on the dead flesh left from the ulcers and other bacterial problems.

Preventing Flukes

Quarantining and treating any new koi or goldfish is the key to preventing any infestation of gill flukes. 

More Information About Gill Flukes

• Buyer Beware - The Importance of Quarantine
• Flash Dance - A Closer Look at Parasites

Items You Might Need:

Parasite Pak

Prazi Pond

Anti-Fluke

Fluke Tabs

Doc's De-Chlorinator

FuBa Fix
Bacterial / Fungus Treatment

Know Your Gallons!

Heavy Duty Water Meter

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