130G DT Peroxide Dosing for Velvet - Experiment

[Johnd651]

TLDR, I got velvet from a coral vendor in the DT, and will be using a 9 week H2O2 peroxide dosing regimen to battle it. Lost 3 of 10 fish. My 6 yo daughter has been sad, since all 3 where gifts to her.

So after this weekend, and my den looking like an aquatic emergency room, I did want to do a write up, and track what I am seeing as I go through this DT peroxide dosing process. DT is a custom acrylic 56x24x26in mixed reef, with sump for a total of about 150 gallons.

Morning of Wednesday, 1/7/2026 I had 10 fish. Whitetail bristletooth tang, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, coral beauty angel, dottyback, and royal gramma.

Afternoon of Wednesday, 1/7/26, I found my Royal Gramma split in half. Everyone was swimming that morning. I assumed that the Dottyback and Royal Gramma got into it, and then the CUC did the rest. I did not see any markings on the Royal Gramma, but it was a small piece left only.

That night I did see the Dottyback hiding in a cave, and the other 8 fish swimming as usual. Thursday, I could not find the dottyback anywhere in the tank. I did some moving of rock, but no luck. The other 8 fish were fine.

Friday morning, 1/9/2026, still only 8 fish, no sign of the dottyback (and I had removed the piece of the royal gramma). My 6 yo daughter loves purple, so she noticed right away that morning before school that her purple fish Blend and Strawberry were missing. Down to 8 fish at this point, Whitetail bristletooth tang, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel.

Came home Friday afternoon and around 4pm noticed my black clown fish had some awful looking soars near its top dorsal fins. It looked like Brooklynella. We had also lost a goat (we have a small farm) 2 nights before to bloat, and my neighbor brought down his Bobcat to dig a hole. I went out with him to get through the gates, and my wife and kid came home and met us out in the field. We finished up and went back inside around 5.

My wife asked why do all the fish look like they have cobwebs/powder on them. I was preparing buckets and nets to try and net the black clownfish. Sure enough, I looked and they all looked like powdered sugar/wet spider webs, similar to Marine Velvet. My first reaction was hydrogen peroxide, since it works on bacteria, but does not just wipe out everything in the tank. I added 20mL of 3% Peroxide directly to the tank, and within about 30 seconds, we saw the sore peel off the clown leaving a red mark, and the sugar start to peel off the fish and float in the water like dust. Of all the fish, the whitetail bristletooth tang was struggling the most. The clown did not look great, but was swimming OK. I tried to catch either one of the two for a peroxide bath (no formalin at home, only peroxide and copper at the moment), but no luck. I did prepare SW for a bath just in case with heater and air bubbler. I also added my emergency backup bubbler directly to the display tank. I did feed them around 8pm, and most fish ate, but the tang did not, and was struggling to keep up right, but he got quick when the net was around.

Around 11PM, I noticed the tang was really slowing down, all other 7 fish where doing ok, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel. I was able to catch the whitetail, and do a 20mL/1 gal peroxide dip with him for 30 min. I returned him to the tank, and dosed the 20mL DT peroxide.

Next morning, 1/10/26 around 7am the whitetail was laying on his side, fins going. I righted him a couple times in the tank. One of those times he finally passed. I continued the DT peroxide dosing regimen. The other 7 fish were doing ok.

Sunday morning, 1/11/2026 I setup and calibrated my 1.7mL/min (actual 20mL/10 min) dosing pump, and have it setup to dose 20mL at 7am, 3pm, and 11pm. The remaining 7 fish are doing ok, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel. The black clown still has red sores. Week 2 (Saturday 1/17/26) I will up the dose to 30mL every 8 hours at 7am, 3pm, and 11pm. Week 3 (Saturday 1/24/26) through end of Week 9 (Friday 3/13/26) will be 30mL every 8 hours at 7am, 3pm, and 11pm, AND 1am to 7am 2.5mL every 15 mins (24 doses). It will be in the range of 2-4mL based on the fact that the timer is set by minute.

I will try and document the tank throughout this process. At this point, we have a 2 month window before we can make any changes in the tank. But if anyone wants to donate a whitetail or some purple fish, my daughter would be ecstatic.

At this point, I do track everything going into the tank, testing, and any changes to the tank. The last thing added to the tank was 3 SPS corals on 12/23/25. Prior to that was a few fish that were in QT since beginning of November. No new equipment, no rock, no sand, nothing else. Dosing has been the same. At this point, the only change within the velvet life cycle is the corals.

Thanks @Humblefish and @pwfess for the help in the moment.

 

[Jay Hemdal Verified Community Expert]

TLDR, I got velvet from a coral vendor in the DT, and will be using a 9 week H2O2 peroxide dosing regimen to battle it. Lost 3 of 10 fish. My 6 yo daughter has been sad, since all 3 where gifts to her.

So after this weekend, and my den looking like an aquatic emergency room, I did want to do a write up, and track what I am seeing as I go through this DT peroxide dosing process. DT is a custom acrylic 56x24x26in mixed reef, with sump for a total of about 150 gallons.

Morning of Wednesday, 1/7/2026 I had 10 fish. Whitetail bristletooth tang, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, coral beauty angel, dottyback, and royal gramma.

Afternoon of Wednesday, 1/7/26, I found my Royal Gramma split in half. Everyone was swimming that morning. I assumed that the Dottyback and Royal Gramma got into it, and then the CUC did the rest. I did not see any markings on the Royal Gramma, but it was a small piece left only.

That night I did see the Dottyback hiding in a cave, and the other 8 fish swimming as usual. Thursday, I could not find the dottyback anywhere in the tank. I did some moving of rock, but no luck. The other 8 fish were fine.

Friday morning, 1/9/2026, still only 8 fish, no sign of the dottyback (and I had removed the piece of the royal gramma). My 6 yo daughter loves purple, so she noticed right away that morning before school that her purple fish Blend and Strawberry were missing. Down to 8 fish at this point, Whitetail bristletooth tang, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel.

Came home Friday afternoon and around 4pm noticed my black clown fish had some awful looking soars near its top dorsal fins. It looked like Brooklynella. We had also lost a goat (we have a small farm) 2 nights before to bloat, and my neighbor brought down his Bobcat to dig a hole. I went out with him to get through the gates, and my wife and kid came home and met us out in the field. We finished up and went back inside around 5.

My wife asked why do all the fish look like they have cobwebs/powder on them. I was preparing buckets and nets to try and net the black clownfish. Sure enough, I looked and they all looked like powdered sugar/wet spider webs, similar to Marine Velvet. My first reaction was hydrogen peroxide, since it works on bacteria, but does not just wipe out everything in the tank. I added 20mL of 3% Peroxide directly to the tank, and within about 30 seconds, we saw the sore peel off the clown leaving a red mark, and the sugar start to peel off the fish and float in the water like dust. Of all the fish, the whitetail bristletooth tang was struggling the most. The clown did not look great, but was swimming OK. I tried to catch either one of the two for a peroxide bath (no formalin at home, only peroxide and copper at the moment), but no luck. I did prepare SW for a bath just in case with heater and air bubbler. I also added my emergency backup bubbler directly to the display tank. I did feed them around 8pm, and most fish ate, but the tang did not, and was struggling to keep up right, but he got quick when the net was around.

Around 11PM, I noticed the tang was really slowing down, all other 7 fish where doing ok, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel. I was able to catch the whitetail, and do a 20mL/1 gal peroxide dip with him for 30 min. I returned him to the tank, and dosed the 20mL DT peroxide.

Next morning, 1/10/26 around 7am the whitetail was laying on his side, fins going. I righted him a couple times in the tank. One of those times he finally passed. I continued the DT peroxide dosing regimen. The other 7 fish were doing ok.

Sunday morning, 1/11/2026 I setup and calibrated my 1.7mL/min (actual 20mL/10 min) dosing pump, and have it setup to dose 20mL at 7am, 3pm, and 11pm. The remaining 7 fish are doing ok, 2x clowns, lawnmower blenny, metallic foxface, social fairy wrasse, firefish, and coral beauty angel. The black clown still has red sores. Week 2 (Saturday 1/17/26) I will up the dose to 30mL every 8 hours at 7am, 3pm, and 11pm. Week 3 (Saturday 1/24/26) through end of Week 9 (Friday 3/13/26) will be 30mL every 8 hours at 7am, 3pm, and 11pm, AND 1am to 7am 2.5mL every 15 mins (24 doses). It will be in the range of 2-4mL based on the fact that the timer is set by minute.

I will try and document the tank throughout this process. At this point, we have a 2 month window before we can make any changes in the tank. But if anyone wants to donate a whitetail or some purple fish, my daughter would be ecstatic.

At this point, I do track everything going into the tank, testing, and any changes to the tank. The last thing added to the tank was 3 SPS corals on 12/23/25. Prior to that was a few fish that were in QT since beginning of November. No new equipment, no rock, no sand, nothing else. Dosing has been the same. At this point, the only change within the velvet life cycle is the corals.

Thanks @Humblefish and @pwfess for the help in the moment.

I’m not sure you’re dealing with Amyloodinium (true velvet). The tang looks to have advanced ich.

Velvet causes rapid breathing, not eating and hanging in water currents. Death often follows in a few days.

Here is an article I just put together on self-diagnosis of common marine fish diseases:

https://www.reef2reef.com/threads/self-diagnosis-of-common-marine-fish-diseases.1141555/

 

[MnFish1]

Agree. I Wonder about injury for a couple of the fish (what exactly is your clean up crew. I see Ich - and velvet does not necessary present with the powder, etc. in marine fish - but rather breathing difficulties as already mentioned by @Jay Hemdal . Agree, in any case, to keep everyone updated - and also - if you could give more information about when the fish were put in the tank.

My opinion is that if it were velvet you would have much higher mortality as well. any further information would be great to have

 

[MnFish1]

Any more information on the tank?

 

[Johnd651]

Any more information on the tank?

After I stopped dosing remaining fish have been fine. Tank did go through a mini cycle. Did not see any major changes up CUC. I will be adding qted fish in about 2 weeks.