Marine Velvet and Snails

[wasp]

I've just had an outbreak of Marine Velvet disease in one of my tanks, and have removed the fish for treatment and to allow the tank to go fallow for 8 weeks.
I've also done a heap of web searching on the topic, and one thing I read stated that if removing fish from a tank to let the parasites die, it is also nessecary to remove inverts, as they can host the velvet parasites also and thus allow the cycle to continue even without fish. Trouble is, it did not say which inverts.
This tank contains a small kind of snail that breed prolifically, be virtually impossible to get them all out.
Does anyone know if this may be a problem?

[GTR]

http://edis.ifas.ufl.edu/VM004
http://www.wetwebmedia.com/amylloodiniumart.htm
SteveU

[mesocosm]

Greetings All !


Excellent links Steve ... as usual!

... it is also nessecary to remove inverts, as they can host the velvet parasites also and thus allow the cycle to continue even without fish.

I'm unaware of any peer-reviewed literature documenting invertebrates as hosts for marine vertebrate parasites such as Amyloodinium ocsellatum ("Marine Velvet").

Amyloodinium is a dinoflagellate that is highly adapted to parasitism. ... The trophont attaches to and feeds on the host's epithelium. After the trophont feeds for seveal days, it detaches from the host ... and becomes a tomont. The tomont divides, producing up to 256 motile, infective dinospores. ... The dinospores attach to a host, differentiate into a trophont, and continue the cycle.

Extracted from:
Fish Disese. Diagnosis and Treatment.
Edward J. Naga, Blackwell Publishing, 2000.

While I have no doubt that invertebrates ... and live rock, food, and seawater for that matter ... can serve as vectors to introduce trophonts, tomonts, and/or dinospores into a system, I have yet to see documentation that invertebrates can serve as "hosts".

Correlation does not imply causation ...

Having said that ... the database IS constantly evolving ... does anyone have any links to peer-reviewed literature citing invertebrate gills and/or epithelial tissue as being capable of hosting Amyloodinium? I may have missed something ... TIA!

My point is ... the removal of all vertebrate hosts from the system for a period of time which will (1) allow all tomonts to mature into dinospores, (2) allow all dinospores to mature into trophonts, and (3) allow all trophonts to die in the vain search for a host, should eliminate Amyloodinium from the system by virtue of a disruption of its life cycle.

I would think that your 8 week timeframe would be more than adequate.

HTH ...

[wasp]

Thanks - hoped that would be the case.