Aquasonic Formalin Malachite Solution (1L) – Treatment for White Spot Disease
White spot disease is a common fish parasite that can be introduced via new fish, plants, etc. These parasites appear as distinct small white spots (pin head size) on the fish’s body and fins. Unless prompt action is taken fatalities will occur.
Directions for Use
- Not to be used on fish intended for human consumption.
- Ensure aquarium water is well aerated during treatment.
- Activated carbon will remove this product from aquarium water, resulting in ineffective treatment. Remove from filtration system during treatment.
- This product contains a dye that will stain if spilled.
Dosage Rates
Use at the rate of 5mL per 20 litres of aquarium water. Harmful to corals. Do not overdose. Repeat treatment as necessary.
| Parameter | Value |
|---|---|
| Volume | 1L |
| Active Ingredient | Formaldehyde and malachite green |
| Usage | For treating white spot disease in fish |
| Caution | Harmful to corals; avoid use in coral tanks |
FAQ
Can this product be used in a tank with corals?
No, this product is harmful to corals and should not be used in tanks containing coral species.
Is it safe to use on fish meant for human consumption?
No, this product is not safe for fish intended for human consumption.
How long should the treatment run?
The treatment should continue until the white spots on fish disappear, typically 3 to 7 days depending on severity. Repeat treatment as needed.

William Greene –
Effective against white spots on my goldfish. Followed the dosage instructions carefully and saw improvement within 4 days. Removed the filter during treatment and kept the tank well aerated. The dye stain was noticeable if spilled, but otherwise the product worked well.
Anthony Alsop –
Used it after introducing new fish. The white spots appeared quickly, and the treatment helped eliminate them. I made sure to remove the activated carbon filter. A bit messy due to the dye, but effective.
Audrey Stewart –
It reduced the white spots, but I noticed some fish became lethargic during treatment. I think the dosage might have been a bit high. Would recommend checking the instructions again.