Hydrogen Peroxide for treating Velvet


Dr. Fish
Premium Member
Hydrogen Peroxide *** The information contained here is subject to frequent changes as I experiment and learn more about the usefulness of H2O2 ***

What It Treats – Provides temporary relief for Marine Velvet Disease. After a 30 minute H2O2 bath, the fish should be transferred into a Quarantine Tank (QT) and treated with either copper or Chloroquine phosphate.

How To Treat – The following is needed:

1. 3% Hydrogen Peroxide (USP grade) - available at most drugstores or Walmart
2. Large glass bowl or container (Avoid using plastic buckets/containers)
3. Syringe or pipette (for measuring out the H2O2) and measuring cup (for adding saltwater to the glass bowl)
4. Metal spoon for mixing (NOT plastic)



1. Prepare saltwater for the bath by having it set to the right temperature and heavily aerating it. You can accomplish the latter by running an airstone or pointing a powerhead towards the surface of the water for at least 1 hour (longer is better). Alternatively, you can use Display Tank (DT) water or even from your Quarantine Tank (QT) provided no medications/chemicals are present in the water.

2. Add saltwater (using measuring cup) to the large glass bowl. Keep track of exactly how much water is added - either in cups or ml. (Do this beforehand if preparing saltwater for the bath right in the glass bowl.) Make sure your fish has enough water to swim around and last for 30 minutes without aeration.

3. Discontinue all aeration before adding Hydrogen Peroxide to the water. Using a syringe or pipette, add 3% Hydrogen Peroxide as per dosing instructions below. Dip the tip below the waterline and spread the H2O2 throughout the water. (Do not allow any air/bubbles to enter the water at this point.) After dosing is complete, gently stir the water using a metal spoon. The reason you want to be careful not to create any gas exchange/aeration once the H2O2 has been added is to prevent the atoms from releasing their bond and becoming just oxygen + water.

Dosing instructions: To achieve ~ 75ppm H2O2 add:

1.25 ml of 3% H2O2 per 2 cups of saltwater. It's okay to overdose slightly.


2.5 ml of 3% H2O2 per 1 liter of saltwater. It's okay to overdose slightly.

4. Now it's time to add the fish. Again, do not aerate during treatment. The bath water should be perfectly still. It's okay to use a heater, but probably not necessary since the bath only lasts 30 minutes. Observe closely and remove the fish if showing signs of distress. The vast majority of fish will handle it just fine. After 30 minutes, remove the fish and transfer into a QT for further treatment: https://humble.fish/velvet/

Pros – Effective, easy-to-source “pre-treatment” before fish is placed in QT with copper or Chloroquine. In this study, a single 30 minute treatment with 75 ppm hydrogen peroxide "greatly reduced" Velvet trophonts on the fish: https://www.researchgate.net/public...n_the_Pacific_Threadfin_Polydactylus_sexfilis

Cons/Side Effects – Still experimental so side effects are not really known. It's possible some fish may not tolerate this treatment.

*** Further reading on use of Hydrogen Peroxide for fish:

http://edis.ifas.ufl.edu/fa157 (PDF: https://agrilifecdn.tamu.edu/fisher...-Hydrogen-Peroxide-in-Finfish-Aquaculture.pdf)



More info from the aforementioned study: https://www.academia.edu/23793309/T...n_the_Pacific_Threadfin_Polydactylus_sexfilis
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Dr. Fish
Premium Member
In the future, I believe many other pathogens can be treated (or even eradicated) by using Hydrogen Peroxide.

However, I feel it's wise to start off conservative with this and only recommend what was been proven thus far. I want to gain more confidence & do more experimentation before recommending a more aggressive treatment protocol for a wider range of parasites/diseases.