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Pond - Anti-Parasite & Fungus

Pond - Eradick
Fluffy white growths, fine white spots
Formaldehyde Active Ingredient
Malachite Active Ingredient


When to use?

  • A five-day course of treatment for when fish show symptoms of parasitic infection, such as irritation, flicking, gasping at surface, covered in thick opaque mucus or visible white spots on the body.
  • Use if fish show signs of a fungal infection which can appear as cotton wool-like growths on the body and as a preventative in early spring. Eradick can be applied directly to leeches and lice, and is safe to use if Pond Salt Plus is present in the water at ‘General Tonic’ level.

How to use?

  • Shake bottle well. Mix the correct dose in a clean bucket of pond water, then pour evenly around the pond.
  • Switch off UV for 10 days from first dose.
  • Wait 10 days after final dose before repeating treatment or applying another treatment.
  • Allow plenty of time to observe the fish and take action in the unlikely event of a reaction.


  • Do not use when the water temperature is above 30°C.
  • Do not use in hot, humid, thundery weather. Do not mix medications.

Find out about the active ingredient in our 'What is Malachite Green?' article.

View our medicinal treatment rules

Q: Is Eradick safe to use with sensitive species, such as orfe and sturgeon? A: Yes. As with all medicinal treatments, however, you should still provide additional aeration, keep an eye on your fish throughout the course of treatment and avoid use in hot, humid or thundery conditions.
Q: Can I use Eradick with salt in the water? A: Yes, provided this is at a concentration of 0.3% (3g/L) or lower. To accurately measure the salt concentration of your pond, use a hydrometer or ask your local fish shop to test a sample for you.
Q: Do I apply the full dose daily for 5 days? A: Yes. Follow the instructions on the back label to work out the dosage you require (or use our Dosage Calculator) and apply this dose daily for 5 days, following any additional instructions shown on the back label. For example, to treat a pond of 10000 litres (2200 gallons), apply a 110ml dose on day 1, another 110ml dose on day 2, again on day 3, and on day 4 and on day 5 of the treatment.
Q: How often can I repeat the treatment? A: After you have added the final dose (on day 5), wait 10 days then perform a partial water change before re-treating or applying a different treatment.
Q: Can I leave my UV on during treatment? A: No, you should turn any UV filters off for 10 days from when you add the first dose.
Q: Will Eradick affect my water quality test results? A: No, so long as the colour has faded from the water. This should happen within a few days of the product being added.
Q: I have a lot of wildlife visitors to my pond. Can I still treat with Eradick? A: Yes, the working concentration of the product is at a non-toxic level for fish, amphibians, birds, etc.

For common frequently asked questions, click here.


Related Products

Looking for more? Find our Medikoi range here.








Active Ingredients: Malachite Green 500 mg/100ml, Formaldehyde 4890 mg/100ml 

Available in the following variations:

250ml, 500ml & 1 Litre

Where to Buy?

Simplified map of the United Kingdom.

Or find a worldwide stockist.


Let us calculate your dosage for you!

To make the process of using our products even easier this handy dosage calculator tells you the amount you will need to put into your system. Please ensure you also read the instructions and warnings that are written on the bottle/pack label.

Note: This calculator does not take into account water displacement such as that caused by substrate, ornaments, water features and plants etc. Therefore, please adjust the calculated volume accordingly.

I know my system's measurements and want to:

Calculate my volume
Dosage calculator

Calculate dosage

You’ll require*
0 ml

10 ml per 200 gallons (909 litres) Apply daily for 5 days.

* Always follow the instructions on the label. This calculator is intended to be used only as a guide to how much product you need to buy to treat your system. It does not take account of displacement caused by gravel, rocks and ornaments etc and does not include the volume of any external filtration system. NT Laboratories Ltd. will not accept any responsibility for inaccuracies or misuse of this guide.