Praziquantel for Koi flukes and trematodes

Praziquantel: How to Treat Flukes or Trematodes and Worms in Fish

Praziquantel for Flukes
Written by Dr Erik Johnson
Praziquantel – (branded Droncit/Prazi/Prazipro)

What it is: Praziquantel is a bitter tasting powder which shows good absorption directly from the treated water, and then admirable clearance of various surface and internal flukes (trematodes) and internal worms in fish.

Praziquantel for Koi flukes and trematodes
Praziquantel for Koi flukes and trematodes

What it’s good at: Because it’s gentle, Praziquantel is, and always has been, the “treatment of choice” for Flukes (trematodes) in fish. Praziquantel does not require water changes, praziquantel is harmless to fish of *all* species including Discus, Koi and goldfish fry, and is non toxic to plants, and; (unlike Formalin), praziquantel has no negative filter impact.

Praziquantel at Retail Amazon

Background: Praziquantel has been known to the hobby for many years. The drug is simply put in the water and within just a few hours the infected fish shed the adult parasites from their intestines. (This medicine treats intestinal cestodes, NOT nematodes) Long tapeworms are sometimes found on the bottom of the treatment tank. It was determined also that the Praziquantel was effective at killing and stopping Fluke (monogenetic trematode) infections. Repeat dosing is usually recommended but this concept should be verified.

Prazi is very effective against Flukes. It is entirely conceivable that the (livebearing) flukes can be eradicated with only one treatment if the Prazi is left in the water to intercept eggs as they hatch. Stop carbon and UV during treatment.

Praziquantel was traditionally available in the form of branded Droncit tablets, for oral administration in dogs and cats. The average retail (vet) price was something on the order of four dollars per tablet which only contained thirty four milligrams.
Considering the proper dosing of praziquantel, the cost of treating a thousand gallons of water would normally be $908.23

Even with Biltricide, the cost of praziquantel was daunting.

Lately, the drug has become available such that it can be deployed for about $20 per thousand gallons to be treated.

The recommended dose of Praziquantel is 2 milligrams per liter of water. This means that in 100 gallons of pond water you would need about seven hundred milli-grams. In a thousand gallons you would need about seven grams of Praziquantel.

The drug is simply stirred vigorously into a liter of clean water and, when mostly dissolved, the white colored suspension is deposited into a high-flow area of the pond. If the fish ingest some of the medicine as it settles out, it’s not a problem. Discontinue carbon and UV during treatment to avoid inactivation of the Praziquantel. You do not need to bypass the filter nor worry about oxygen levels during treatment. The most successful treatments are deployed in cleaner ponds, so any excess leaf litter or debris should be removed. Clearance of the flukes can be determined (ideally) by microscopy or the overall improvement of signs of flashing and scratching. On occasion, segments or ribbons of worms may be passed in the fish stools and are generally of no concern to human health. No sifde effects as far as fish behavior or health have been reported or expected.

If you’re treating a Fluke infestation, traditional wisdom suggests a single repeat treatment in four to five days after the first treatment to kill emerging larvae which may have been shielded from treatment by the mother-fluke or the egg.

Pros: The advantages are that Praziquantel is entirely benign to plants, fish and filter while clearing the Flukes and intestinal worms out rapidly and completely, even with fry.
Now, it can be considered that praziquantel is the least-expensive specific aquacultural Fluke treatment for ornamental ponds. When you consider that it requires only one or two doses and does NOT require water changes, nor plant removal, nor increased water agitation, this remedy is even superior to Supaverm by price and safety. Fluke Tabs are gone. (2018)

Testing remains to be done to see how Flukes clear with Mardel’s CLOUT.

Cons: Still not cost effective for lakes and natural ponds.
Non specific Fluke remedies such as Formalin or Potassium permanganate are not risk free.

Precautions: Do not use on food fish or fish intended to be used as food. Keep out of rach of children. Do not take internally except by or on the order of your physician.


Doc Johnson