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The Best Way to Dissolve Praziquantel

And How to Effectively Treat Flukes in Koi & Goldfish
how to dissolve praziquantel

Why Use Praziquantel?

Praziquantel is a white powder that is used primarily as medication for parasitic worm infections in humans and animals. Luckily, it can also be used in ponds, aquaculture and aquariums. Praziquantel (prazi) is a safe and effective treatment for skin flukes (Gyrodactylus sp.) and gill flukes (Dactylogyrus sp.) in ornamental fish such as koi and goldfish, as well as tropical fish commonly kept in aquariums. Plus, it is also effective at treating tapeworms in fish. Unlike some other medications, Prazi is is gentle on fish, is safe to use with plants, and won’t negatively affect your biological filter.

gill and body flukes in koi

Skin Flukes (Gyrodactylus sp.) shown above 

Difficulties Dissolving Praziquantel

Praziquantel must be dissolved in the water to kill flukes and tapeworms. However, praziquantel is notoriously hard to dissolve in water, making it difficult to effectively treat the fish. If you have used praziquantel before, you know what I mean.

While there are liquid forms of Praziquantel medication, I find that the prazi often precipitates out of solution, and you are usually left with a lot of gooey prazi at the bottom of the container that still needs to be dissolved in the pond water.

My Attempts at Dissolving Praziquantel

Over the years, I tried various methods to dissolve praziquantel, and each method I found, seemed to work better than the last, but I wasn’t satisfied with any of them. With most of these methods, the prazi would only partially dissolve, leaving a lot of powder and clumps of prazi just floating on the surface of the water. 

  • When I first started using praziquantel, I would mix the it with very hot water in a water bottle and shake the bejesus out of it. Some of it dissolved, but no matter how hard, or how long I shook it for, most of the prazi would’t dissolve. I really wasn’t happy with the results.
  • Next, I mixed it with Microbe Lift Broad Spectrum Disease Treatment (Proform C), which is a formalin / malachite green based medication. Again, I  placed it in a bottle and shook it vigorously. The results were better, but not as good as I would have liked. When I applied it to the water, there was still a significant amount of undissolved prazi floating on the surface. However, this combination does provide a nice ‘1-2 punch’ if you think there may be more than just fluke outbreak.
  • Still wanting better results, I kept researching, until I came across using vodka (yes, Vodka!)to dissolve it. So, naturally I tried this, and I must say it worked quite well. the prazi dissolved quite well, but I thought it was a terrible waste of  good vodka. There had to be a better way.

The Solution

Finally, after many different attempts, I found the best way to dissolve praziquantel in water. While working at a Ripley’s Aquarium, I learned how they administer it. This method is simplest and most effective way to dissolve the prazi quickly and easily, and it can be summed up in one word…….pantyhose. Yes, pantyhose.

Instructions For dissolving Praziquantel:

  1. Measure the desired amount of praziquantel and place it into a nylon stocking or pantyhose 
  2. Tie off the top of the stocking, so that the prazi doesn’t escape.
  3. Simply immerse the stocking in the pond or aquarium, and gently roll the stocking between your fingers. (remember to always wear gloves when working with medications)
  4. You will notice that the prazi immediately comes out of the stocking as a white cloud in the water. It will quickly disperse in the pond or aquarium. 
  5. Continue rolling the stocking until there is no prazi left inside. This usually takes 3-5 minutes, depending on how much prazi you are adding.
nylon stocking used to dissolve praziquantel

Direction For Treating Flukes With Praziquantel

Dosage Rate For Praziquantel: Prolonged Immersion

A prolonged immersion is what we recommend treating for flukes. Simply put, this means you are going to add the medication to the pond or aquarium, and leave it indefinitely, rather than doing a dip or bath for a shorter amount of time. This is the most effective way to treat flukes in your pond, because if one of your koi has flukes, there is a good chance that several others do as well. Plus, treating the pond will help kill any flukes that are ‘hiding’ in the filter or on the bottom of the pond.     

Dosage Rate 

  • 1 gram per 100 gallons of water.
  • For example, a 1200 gallon pond requires 12 grams of praziquantel.

Application of Praziquantel:

  • Remove any carbon / charcoal from your pond or filter.
  • Turn off your ultraviolet clarifier. 
  • There is no need to bypass your biological filter.
  • Apply the appropriate amount of prazi to your pond.
  • If needed, reapply after 4 to 5 days.
  • A partial water change can be done 7 days after the last treatment, but is not necessary.

Treatment Recommendations:

Skin Flukes:

For skin flukes, 1 treatment is often enough. Since body flukes reproduce by giving birth to live young, one dose of prazi usually kills both adult and juvenile skin flukes. If you have a particularly bad outbreak, a second treatment is recommended

Gill Flukes:

For body flukes, at least 2 treatments are need, spaced 4 or 5 days apart. Gill flukes reproduce by laying eggs, and like most parasites, their eggs are immune medications. This means that the first treatment will only kill the adult and juvenile flukes, but not the eggs. The second treatment is needed, usually after 4 or 5 days, to kill next generation of flukes once they hatch.

About the author

Graduated from the University of Guelph with a B.Sc. (Hons) Marine Biology. With over 30 years experience in the aquarium / pond industry, his passion for fish includes ponds, marine aquariums and water features of all sizes. Previous work includes Ripley’s Aquarium, the Toronto Zoo, Bass Pro Shops, Rainforest Cafe and the National Museum of Kenya.

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