Velvet question

[Indeco]

Recently I heard a reefer sharing his story on how velvet crushed his tank but after hearing it a question pop up in my mind.

Here the story go...

The reefer brought 4 new fishes (Blue Tang, Purple Tang, Powder blue tang, trigger) and was doing his due diligence to quarantine them for a month. During these period all fishes are eating well and no diseases or illness are spotted. He did not do any medical treatment during this QT period.

After QT period, he started introducing the fishes into the tank and soon he realised that the powder blue tang started to show sign of ich like symptom.

Unfortunately he did not react in time and by the time he knew it is not ich, it just too late.

So, is the powder blue tang having velvet but due to strong immunity system it did not react during the QT period? Or the velvet exist in the main tank and when the powder blue is introduced in, it got affected.

It is possible for fishes to resist velvet? My understanding is only few fish with very thick mucus will be able to handle it.

[nereefpat]

We'll never know for sure...

My guess is that velvet was present in the display. What other fishes were in the display before the tangs were added?

[Indeco]

Fishes are clown fish, blenny, wrasse, flame angel, flame hawk

If velvet in present in display tank, possible mean velvet has the ability to "hibernate"?

[nereefpat]

So, all of those fishes have velvet now? All of the tangs?

It's a little confusing. Pics would confirm velvet, or ich, or flukes, or bacterial or whatever.

[Uncle99]

Velvet is a fast killer, maybe 72 hours most.
Looks a bit like ick but the dots are round, not oval like ick

[HumbleFish]

Keep in mind that corals & inverts can carry ich & velvet tomonts, so these should be isolated to a fishless frag tank for at least 6 weeks. Just another possibility to consider.

[ThRoewer]

Keep in mind that corals & inverts can carry ich & velvet tomonts, so these should be isolated to a fishless frag tank for at least 6 weeks. Just another possibility to consider.

The likelihood of inverts carrying ich and velvet cysts is minimal as these parasite's cysts usually avoid to attach themselves to moving objects or living tissue. At least that is the info I got from Rich Ross of the Steinhart Aquarium in SF.

Hermits are a slightly higher risk though as they may have just picked up a different shell that had a cyst attached.
And only the bases (rocks, frag-plugs, dead skeleton,...) of corals can harbor fish parasite cysts, but those would just be food should they land on living coral tissue. So an easy solution for corals is to only use freshly cut frags or at least cut the old frag plug or coral bases off.

As for quarantining inverts - it works with some, usually the ones that don't need it anyway, but not with all. In my experience you may as well flush snails and hermits (and anything else requiring algae as food or having other special requirements) straight down the drain unless you have a fishless tank with lots of live rock and algae and a full scale filter system. And seriously, who has that?
And 6 weeks would of course not be enough either - you would have to go the full 3 fallow months.

Given how minute the risk is I rather put inverts straight in the tank before risking their lives in a questionable attempt to quarantine them.

[ThRoewer]

I had come across a study on immunity against Amyloodinium (velvet) and it seems to be not uncommon with fish from certain regions (his study was done on fish in or near the Mississippi delta).
One finding was that in a confined system (= tank) the weakest fish of all the ones in the tank will succumb to the parasite while all other fish may seem to be unaffected. Once that one is dead the next weakest will fall victim to the parasite.
That may go on until the last fish is done.
This is quite different from Cryptocaryon immunity which actually enables an otherwise fit and healthy fish to live indefinitely with the parasite.

So it is quite possible that only one fish is acutely affected by velvet while all are infected but strong enough to keep the infection at bay.
If you have a case where fish die one by one of symptoms aligning with velvet you may have just such a case as outlined above. As that shows, velvet doesn't necessarily have to be a quick killer but can draw it out quite a bit.

This also makes it far more likely that one of the new fish had an occult Amyloodinium infection than that the parasite was already in the system.

Also, always keep in mind that low dose copper treatment can obscure velvet, ich and other parasites and suppress open outbreaks for up to 6 weeks!
So one month of QT is nowhere near sufficient to be sure the fish are clean.

[ThRoewer]

Studies on Amyloodinium ocellatum (Dinoflagellata) in Mississippi Sound: natural and experimental hosts (https://aquila.usm.edu/cgi/viewcontent.cgi?referer=https://scholar.google.com/&httpsredir=1&article=1125&context=gcr)

For those interested diving deeper into the matter:

https://scholar.google.com/scholar?hl=en&as_sdt=0%2C7&q=immunity+amyloodinium&btnG=

Acquired immunity to amyloodiniosis is associated with an antibody response (https://www.int-res.com/articles/dao/34/d034p125.pdf)

Protective immunity in fish against protozoan diseases (https://pdfs.semanticscholar.org/a298/671cd59e8b2472f307c8f9bd8a19ff26d850.pdf)

Detection of antibody response against Amyloodinium ocellatum in serum of naturally infected European sea bass by an enzyme-linked immunosorbent assay (https://eafp.org/download/2001-Volume21/Issue%203/21_104.pdf)

[HumbleFish]

The likelihood of inverts carrying ich and velvet cysts is minimal as these parasite's cysts usually avoid to attach themselves to moving objects or living tissue. At least that is the info I got from Rich Ross of the Steinhart Aquarium in SF.

Snails are my biggest concern, as they are sometimes stationary and their shells are perfect for encystment. I've read of many velvet wipeouts that started out with, "The only thing I've added lately was some snails."

And 6 weeks would of course not be enough either - you would have to go the full 3 fallow months.

6 weeks is sufficient for every disease except that one strain of Ich. I personally don't have a problem quarantining corals, snails, shrimp, whatever in my 29 gal fishless frag tank (pic below). Just cheap T5 lighting, Koralia powerhead, HOB powerfilter, heater, rock/sand and a frag rack gets the job done. You can spot feed corals/inverts, and give the snails algae wafers and nori.

http://i1276.photobucket.com/albums/y478/Humblefish123/frags/100_2082_zpseba583fa.jpg~original