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NT Labs Formaldehyde


NT Labs Formaldehyde treats: White spot, Trichodina, Costia and Chilodonella.

Grouped product items
Product Name Quantity
NT Labs Formaldehyde 250 ml(KM0014)
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NT Labs Formaldehyde 500 ml(KM0015)
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NT Labs Formaldehyde 1 ltr(KM0016)
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NT Labs Formaldehyde 2.5 ltr(KM0017)
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Starting at £9.99

In stock

NT Labs Formaldehyde treats: White spot, Trichodina, Costia and Chilodonella.

When to use NT Labs Formaldehyde

When fish show symptoms of a parasitic infection, including white spots along the fins and body, flicking and rubbing, gasping at the surface, or an opaque film over the body.
Formaldehyde is highly effective at treating parasites due to its ability to penetrate through the mucus layer, reaching those parasites which would otherwise be protected from alternative bath treatments. It can also be used in conjunction with Malachite to treat protozoan parasites more effectively.

How to use NT Labs Formaldehyde

  • Test your water quality using NT Labs Test Kits.
  • Mix the appropriate dosage in a clean bucket of pond water, pour evenly over the surface of the pond and leave for 7 days. Switch off UV filtration for 5 days. Aerate the pond well during treatment.
  • If you feel a repeat dose is necessary, check your diagnosis carefully using the Diagnosis Tool; a different medication may be more suitable. Allow 7 days and perform a partial water change before re-treating or treating with a different medication.
  • Always treat when you have time to observe fish and take appropriate action in the unlikely event of a bad reaction.

If required, mix with Malachite prior to adding to the pond, following the instructions above.


Do not use with orfe, rudd, tench or sturgeon/sterlet. Do not use if the water temperature is above 30°C. Do not use in hot, humid, thundery conditions. Do not mix medications, other than combining with Malachite.

NT Labs Formaldehyde can be used as a dip bath to treat severe cases quickly. For the bath add 1ml to 1 gallon of pond water and bathe the fish for 1 hour. Aerate the water and watch for signs of stress.

Caution: Formaldehyde is a hazardous chemical and should be handled with great care, please read the warnings on the label carefully.

250 ml treats 17048 litres (3750 gallons)