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Marine Velvet (Amyloodinium)

Amyloodinium ocellatum

Critical severity ⚠️ Contagious

an extremely fast, deadly marine parasite that coats fish in gold dust and attacks the gills

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Symptoms

Catching illness early gives the best chance of recovery, so check your fish daily. A fine gold-brown dust over the skin, rapid gill breathing, flashing, clamped fins and sudden deaths; far faster and deadlier than marine ich. Act promptly if you see several signs together.

Causes

A highly aggressive marine dinoflagellate parasite, usually introduced by new fish, that attacks the gills first and can kill within days. The underlying trigger is almost always stress, poor water quality or a newly introduced animal.

Treatment

Act immediately: treat in quarantine with copper or chloroquine (never in a reef), dim the lights, and improve oxygenation. Prognosis is poor once breathing is laboured, so speed is critical.

While treating, increase aeration, remove activated carbon from the filter, finish the full course even after symptoms fade, and keep the water immaculate. Marine treatments belong in a separate quarantine tank, never the reef.

Prevention

Strictly quarantine all new marine fish, as marine velvet is one of the deadliest and most contagious reef-tank diseases. The golden rules: quarantine new arrivals, never overstock or overfeed, avoid sudden swings, and keep up regular water changes.

FAQ

What is Marine Velvet (Amyloodinium) in fish?
An extremely fast, deadly marine parasite that coats fish in gold dust and attacks the gills.
How serious is Marine Velvet (Amyloodinium)?
It is rated critical severity and is contagious, so treat the whole system promptly.
How do I treat Marine Velvet (Amyloodinium)?
Improve water quality first, then use the correct treatment for the cause (see the Treatment section), removing carbon while medicating and completing the full course.
Can Marine Velvet (Amyloodinium) be prevented?
Yes - quarantine new arrivals, keep water pristine and stable, and avoid stress, which is what lets most diseases take hold.
Will it spread to my other fish?
Yes, it is contagious - treat the whole tank/system, not just the visibly affected fish.

This information is general guidance, not veterinary advice. Consult an aquatic vet for serious cases.

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