Marine Velvet Disease

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Humblefish

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Marine Velvet Disease (Amyloodinium ocellatum)
Amyloodinium-ocellatum-throphont-s-in-gills-of-infected-fish-150x150.png


What You Need To Know:

* Fast killing parasite capable of wiping out most of your fish in just a matter of days. Sometimes there are survivors, sometimes not.
* Can be treated in a quarantine tank using Chloroquine phosphate or Copper. A 5 minute freshwater dip, and 90 minute acriflavine bath (or 45 minute formalin bath) can provide temporary relief before the fish enters quarantine. Once velvet is detected, treatment should begin ASAP!
*
The fallow (fishless) period for starving velvet out of a Display Tank is 6 weeks.
* Symptoms of velvet include swimming into the flow of a powerhead or wavemaker, and tiny white dots on the fins & body. The white dots can look similar to ich, but are smaller and usually far more numerous. If you can count the white dots its usually ich. However, if they are too numerous to count there’s a good chance you are dealing with velvet.

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Velvet 1.jpg

Velvet 2.jpg

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Sometimes with light colored fish the white dots are mostly visible on the fins:

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This shows the difference between ich (1st photo) and velvet (2nd photo) on a Hippo Tang:

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Video of a Moorish Idol with velvet (notice the sheen as he turns):



Understanding Marine Velvet Disease

Amyloodinium ocellatum, commonly referred to as “velvet,” is a single-celled dinoflagellate capable of causing disease in marine fish. Velvet’s life cycle is similar to that of Cryptocaryon irritans (ich). However, there are a few key differences:
  1. Velvet “free swimmers” are referred to as dinospores instead of theronts.
  2. Velvet’s life cycle is typically faster (completed in 4 days on average), and the attacking free swimmers are more numerous than ich.
  3. Velvet dinospores can remain infective for up to 15 days, whereas with ich theronts it’s only 48 hours. This is because velvet tomonts and dinospores are both capable of using photosynthesis as a means of obtaining nutrients (remember it is a dinoflagellate).
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Symptoms – Velvet dinospores will usually invade the gills first and sometimes kill the fish right then due to asphyxiation. If this happens, you may never see physical evidence of velvet on the skin & fins. Therefore, it is important to observe for these key behavioral symptoms of velvet:
  • Reduced or complete loss of appetite.
  • Heavy breathing, scratching, flashing, head twitching, erratic swimming behavior (unfortunately velvet shares all these same symptoms with ich & gill flukes.)
  • Swimming into the flow of a water pump/wavemaker/powerhead (unique to velvet).
  • Acting reclusive (velvet causes fish to be sensitive to light).
If visible physical symptoms do manifest:
  • Velvet may initially start out looking just like ich, with salt or sugar-like “sprinkles” visible mostly on the fins.
  • Within days or sometimes just hours, these tiny white dots will spread all over the fish’s body, covering it in “dust.” This dust may look grey-gold colored if viewed at the right angle and under the right spectrum of light. For this reason, it may be difficult to see velvet on a yellow or light colored fish (look from an angle, not directly from the side). However, sometimes a fish’s body will look “dirty” or show “dark areas” just before velvet appears.
There are two ways to differentiate velvet from ich:
  1. Velvet trophonts (and the correlating dots) are much smaller than ich. They range in size from 10-80 micrometers in diameter. They are also perfectly round. Ich trophonts are more oval shaped and range in size from 48 x 27 to 452 x 360 micrometers. Both start off small but then grow in size before dropping off. It has been said that velvet makes a fish look like it has been dusted with a fine powder, whereas ich is more like salt grains.
  2. If you can count the number of white dots on your fish, then you are probably dealing with ich. If they are too numerous to count, it is most likely velvet.
The importance of recognizing key behavioral symptoms of velvet and then beginning treatment immediately cannot be stressed enough. This is because once velvet has spread to the body, the fish is heavily infected and prognosis is bleak. Velvet cannot usually be managed, as ich sometimes is, due to its sheer overwhelming numbers. Sometimes it is possible in a very large aquarium (i.e. dilution of the free swimmers) if you also utilize equipment (e.g. UV sterilizer, diatom filter) capable of removing free swimmers from the water column. Survivors of velvet are usually clownfish, and other fish with a thick mucous coat like wrasses & dragonets. It is also thought a very small percentage of fish are capable of building up either natural or temporary immunity (usually 6 months max) to velvet.

Treatment Options – Chloroquine phosphate is the treatment of choice for velvet, but copper also works if symptoms are caught early on. These also work on ich, so if in doubt treating with Chloroquine or copper will have you covered both ways. A freshwater dip and/or chemical bath (discussed in more detail below) is recommended either before or during treatment, due to the severity of this disease; however these would only provide temporary relief and will not eradicate velvet.

I personally use the following treatment protocol on fish with velvet:
  1. 5 minute freshwater dip: Freshwater Dip – Marine Fish Diseases and Treatment
  2. 90 minute bath using Ruby Reef Rally. Temperature control and heavily aerate the bath water.
  3. Treat for 30 days in a quarantine tank using either Chloroquine phosphate (60 mg/gal) or chelated copper (e.g. Copper Power – 1.75 ppm).
Final Thoughts
  • You need to move with a sense of urgency when a fish has velvet. This is not the same as dealing with ich. A fish with velvet may have days or just hours to live without prompt treatment.
  • A small percentage of fish are thought to be capable of building up a natural or temporary immunity to velvet (and perhaps other parasites as well). Natural immunity is less understood, but temporary immunity usually only lasts 6 months max. During that time the fish is still a carrier and capable of infecting other fish. Over the years I have noticed this trend: Clownfish, mandarins and other fish with thick slime coats are often the only fish left standing following a velvet wipeout.
  • Disease masking: There is some anecdotal evidence to suggest that fish treated with a non-therapeutic level of copper will not show symptoms of ich, velvet, brook, etc. for weeks. This is why it can be dangerous to buy from LFS who treat their fish with copper but do not test daily to ensure it remains within the therapeutic range.
  • The life cycle of velvet varies according to strain. The trophonts, which feed and do all the damage, can remain on a fish for as little as 12 hours or as long as 4 days. Common sense dictates you are more likely to save a fish with velvet if it’s a “12 hour variant” than one which feeds on the fish for 4 consecutive days, since the medication will not kill the trophonts still on the fish.
  • Even after completing the freshwater dip and chemical bath, you will still see tiny dots all over the fish. This is because the dots you see are not the actual parasites. Velvet, like ich, is invisible to the naked eye in all forms. The dots or “dust” you are seeing is actually excess mucous buildup around where the trophonts are feeding. It will take a few days for this to diminish.
  • If you can’t get acriflavine or formalin right away, daily freshwater dips may buy you more time.
  • As mentioned previously, velvet dinospores (free swimmers) can remain infective for up to 15 days. By contrast, ich theronts only remain active for 48 hours, with infectivity greatly reduced just 6 – 8 hours after it leaves the cyst. What this means is that velvet has a lot more time to seek out and attach to a fish host, which partially explains why a fish with velvet is often covered in it.
  • Velvet doesn’t take much of a break. Velvet tomonts release free swimmers every 4 days (on average). As mentioned above, those free swimmers can hang around for up to 15 days looking for fish to infect. Ich tomonts only release theronts (free swimmers) every 2-4 weeks (on average), with at least one strain taking up to 72 days. Since the trophont (feeding stage) remains on the fish for 3-7 days before dropping off, a fish with ich gets some relief in-between bombardments.
  • Velvet likes light. As a dinoflagellate, velvet tomonts and dinospores are both capable of using photosynthesis as a means of obtaining energy. So when a dinospore ruptures from its cyst, it propels upward (towards the light) by using whip-like appendages for locomotion. Therefore, top swimming fish are probably more at risk than bottom dwellers. I highly suggest not using an aquarium light during treatment and also when running fallow for velvet (if possible in a fish only system).
  • The study on aerosol transmission – which established the 10 foot rule – was done using velvet as the subject of the study. More info on that here: Aerosol dispersal of the fish pathogen, Amyloodinium ocellatum
More info regarding Marine Velvet Disease can be found here: http://agrilife.org/fisheries/files...mportant-Parasite-of-Cultured-Marine-Fish.pdf

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Jessican

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what's the fallow period for velvet? sorry if it's in there and i'm just not seeing it
6 weeks. For reference:

Fallow Periods - Below is the general consensus fallow periods for all diseases that require it. In most cases, it is the longest known time periodthat the encysted stage can survive on corals, inverts, rocks, substrate without a fish host to feed on. The fallow period starts when the last fish is removed from the tank.
  • Black ich (turbellarian worms) - 4 weeks
  • Brooklynella aka “Clownfish disease” or “Brook” - 6 weeks
  • Flukes (monogenean worms) - 4 weeks
  • Ich (Cryptocaryon irritans) - 76 days
  • Uronema marinum - No fallow period, as it does not require a fish host to survive. It is an opportunistic parasite that strikes when a fish’s immune system has been compromised. Uronema mainly affects damsels (especially chromis) and clownfish.
  • Velvet (Amyloodinium) - 6 weeks
 

edwarb17

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6 weeks. For reference:

Fallow Periods - Below is the general consensus fallow periods for all diseases that require it. In most cases, it is the longest known time periodthat the encysted stage can survive on corals, inverts, rocks, substrate without a fish host to feed on. The fallow period starts when the last fish is removed from the tank.
  • Black ich (turbellarian worms) - 4 weeks
  • Brooklynella aka “Clownfish disease” or “Brook” - 6 weeks
  • Flukes (monogenean worms) - 4 weeks
  • Ich (Cryptocaryon irritans) - 76 days
  • Uronema marinum - No fallow period, as it does not require a fish host to survive. It is an opportunistic parasite that strikes when a fish’s immune system has been compromised. Uronema mainly affects damsels (especially chromis) and clownfish.
  • Velvet (Amyloodinium) - 6 weeks

@Jessican @Humblefish

I just want to make sure I understand the lifecycles / time frames from a quarantine perspective - does this mean that if I perform the tank transfer method successfully, then monitoring the fish for 7 weeks (8 to be safe?) in QT should ensure my fish do not have these diseases if they are asymptomatic?

I discovered my QT Tang is intolerant of copper; the first tank he was in had low traces of copper and he was twitching occasionally, which became frequent as I increased the copper levels to therapeutic (never made it). Now he's in a clean QT for his Day 3 transfer of the TTM, and all the twitching has stopped. (FW dip verified he did not have flukes).

I've had horrendous luck with prophylactic treatment (ESPECIALLY with Tangs) so I'm really trying to treat on an as-needed basis. But I would also like to understand how long they have to be in QT for, so they're not trapped in a smaller tank in my basement longer than they need to be and I can get them into a nice big 120g tank to swim freely.
 

edwarb17

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@edwarb17 are you doing just straight TTM, or the hybrid version with peroxide baths? I haven’t had good success with meds either myself, so I would make sure to use the peroxide baths as extra insurance.
I am just doing pure TTM, only because 1. I already did my first transfer (not sure if I can do the H2O2 bath if I already did that? Next transfer is due tomorrow by 9pm)
2. I'm not sure what the tolerances are for 150ppm H2O2? I could calculate the volume filled in my QT to get a best estimate, but I don't know how precise I need to be for effective treatment and what the OD threshold is. and 3. I am absolutely terrified of stressing my fish out by doing this wrong and killing another tang. I've had horrific luck with QT so far so I'm on the "Keep It Simple" train. I cannot emotionally or psychologically deal with another loss; I literally had nightmares about losing my fish the night I performed my first tank transfer.
 

Jessican

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I am just doing pure TTM, only because 1. I already did my first transfer (not sure if I can do the H2O2 bath if I already did that? Next transfer is due tomorrow by 9pm)
2. I'm not sure what the tolerances are for 150ppm H2O2? I could calculate the volume filled in my QT to get a best estimate, but I don't know how precise I need to be for effective treatment and what the OD threshold is. and 3. I am absolutely terrified of stressing my fish out by doing this wrong and killing another tang. I've had horrific luck with QT so far so I'm on the "Keep It Simple" train. I cannot emotionally or psychologically deal with another loss; I literally had nightmares about losing my fish the night I performed my first tank transfer.
You can, you just do the baths prior to the transfers on days 4 & 10 instead of 1 & 7. Regular TTM won’t work for velvet, you have to do either the hybrid TTM or the modified schedule for velvet. Hybrid has the additional benefit of also probably eliminating brook.

For what it’s worth, I’ve only had one fish that didn’t seem to handle the bath well, and that was a cleaner wrasse. As far as I recall, others who had issues were dealing with wrasses as well (but in that case, they were also testing a longer and maybe more concentrated bath I think). In any case, I expect that tangs would be fine. And if it’s right before a transfer anyway, you can always abort the bath if you see any sign of distress.

As for concentration, if you’re worried about it, I’d just underdose a bit. Previously the recommendation was 75ppm, but @Humblefish upped it to 150ppm after seeing that fish seemed to handle that fine, so I’d say you have some wiggle room. How big is your QT?
 
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dumb question, but if we know h2o2 doesn't completely work on velvet after 1 bath, do we know it works after 2? or am i just remembering that one recent case where h2o2 seemed to knock off most parasites, but then they returned a week later?
 

edwarb17

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You can, you just do the baths prior to the transfers on days 4 & 10 instead of 1 & 7. Regular TTM won’t work for velvet, you have to do either the hybrid TTM or the modified schedule for velvet. Hybrid has the additional benefit of also probably eliminating brook.

As for concentration, if you’re worried about it, I’d just underdose a bit. Previously the recommendation was 75ppm, but @Humblefish upped it to 150ppm after seeing that fish seemed to handle that fine, so I’d say you have some wiggle room. How big is your QT?

Oh, that's promising! Maybe I'll take a stab at the peroxide tonight before transfer 4. I think I have some that hasn't expired.

My QT tanks are 20g. This tang is the largest fish I've had in QT but was less concerned because (prior to ttm) I had an abundance of beneficial bacteria built up. I generally prefer fish in their juvi stages so they can grow with the tank. He's definitely pushing limits, though.
 

Jessican

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dumb question, but if we know h2o2 doesn't completely work on velvet after 1 bath, do we know it works after 2? or am i just remembering that one recent case where h2o2 seemed to knock off most parasites, but then they returned a week later?
I don’t think we know that yet for sure. If I’m remembering correctly, @Humblefish said that guy may have cross contaminated.
 

Humblefish

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dumb question, but if we know h2o2 doesn't completely work on velvet after 1 bath, do we know it works after 2? or am i just remembering that one recent case where h2o2 seemed to knock off most parasites, but then they returned a week later?

One H2O2 bath resulting in 100% eradication is something that's still being studied.

However, this study proved that two H2O2 baths (spaced 6 days apart) achieved that goal for velvet: https://www.researchgate.net/public...n_the_Pacific_Threadfin_Polydactylus_sexfilis
However, single treatments with hydrogen peroxide at concentrations of 75 or 150 mg/L eliminated Amyloodinium sp. trophonts without causing loss of fish. In the field trial, a single treatment with 75 mg/L hydrogen peroxide greatly reduced levels of Amyloodinium infestation, and a second treatment 6 d later reduced Amyloodinium trophonts to a nondetectable level. These findings suggest that hydrogen peroxide is a suitable chemical for the treatment of amyloodiniasis of cultured, juvenile Pacific threadfin.
 

Poochaku

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How long does it take for velvet to show in a tank? I'm assuming this depends on the load initially spread in the tank. I'm trying to narrow down the reasons I might have gotten velvet through timing.
 

Humblefish

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How long does it take for velvet to show in a tank? I'm assuming this depends on the load initially spread in the tank. I'm trying to narrow down the reasons I might have gotten velvet through timing.
It usually takes a week or two for symptoms to really become noticeable. Of course, if you are running a UV or feeding really well or dosing a herbal remedy, etc. etc. ... all bets are off.
 
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