Marine Velvet (Amyloodiniosis)

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Parasitic outbreak – diagnosis, prognosis, prevention and cure

This article was contributed by Aquarium Advice member quarryshark

Marine Velvet (Amyloodinium ocellatum) is one of the more problematic parasitic diseases encountered by hobbyists. Only Cryptocaryon (marine ich) is seen more frequently by aquarists. Mortality is nearly certain in the advanced stages of Amyloodiniosis and diagnosis is difficult due to the lack of outward physical markings in the early stages. Heavy infestations tend to occur within the gill filaments and death can occur within a day once this stage is reached. Quick, proactive treatment is needed to save the infected animal and early detection is desired. Once the parasite is introduced into a closed system, all fish must be removed to a hospital quarantine setting and treated accordingly. Amyloodiniosis has been known to wipe out entire fish populations within a week of introduction, so the best course of action is to quarantine all new arrivals for a period of four weeks before placing them in the display tank. This parasite is usually brought into a system with newly-arriving fish, but can also be brought in (less frequently) from invertebrates, corals, live rock, etc, in its tomont stage.

Life Cycle: The life cycle of Amyloodinium ocellatum should be understood in dealing with an infected fish or system, it has a 3 stage life cycles.

1. Trophont – The stage in which the parasite becomes attached to the host fish either on the body or the gill filaments. Here the trophozoites grow and mature, getting their nutrients from the host fish. Once they reach maturity (3-7 days) they then drop off the fish and encase on the substrate in the tomont stage.

2. Tomont – In this cystic state the tomonts undergo internal division and emerge in greater numbers to the free-swimming state called dinospores.

3. Dinospore – In this free-swimming state the parasites reattach to the host fish to start the cycle over again in greater numbers until the animal becomes overwhelmed and perishes. Dinospores remain in this free-swimming stage, seeking a host usually for 7-8 days, but some have been found to survive as long as 30 days. It is in this free-swimming state that the parasite is vulnerable to treatment.
It is also worth noting that Amyloodinium can complete its life cycle in as little as 3-6 days. This short life cycle, coupled with the fact that each new tomont can release as many as 256 free swimming dinospores, is the primary reasons why death from this parasite is so abrupt. Without quick intervention, the gill filaments can quickly become overwhelmed and damaged, causing the fish to suffocate.

Symptoms and Prognosis:

The difficulty in dealing with this parasite is diagnosing its presence. Unlike Cryptocaryon, physical markings are usually not detected until the later stages of infestation when the animal is already near death. Early detection is paramount if a successful treatment is to be implemented.

The early signs include loss of appetite, rapid respiration rate (about 80 times a minute), general lethargy, swimming or hovering in one part of the tank (usually near the surface or by a power head) and scratching (flashing) on substrate, rock or tank decorations. In the advanced stages there may be golden or white dusty-looking patches on the body, or around the gills. Unfortunately, once this stage is reached, the fish will usually perish within a few hours from a lack of O2.


The only practical, effective treatment for amyloodiniosis is copper. All fish (hosts) must be removed from the infected system and treated in isolation (quarantine) hospital tank(s). The parasite is only vulnerable in its free-swimming (dinospore) state, so the copper must be maintained at the manufacturer’s recommended dosage for 14-21 days. A 21-day period of copper treatment is the best way to ensure that the parasites at all stages have completed their life cycle and have been eradicated. After the copper treatment is complete, the fish should remain in the hospital tank for another 5 weeks for observation to ensure against reinfection.

The copper medicine that I recommended for this treatment is Cupramine by Seachem. It is a non-chelated copper and is well tolerated by most fish. It is also imperative that the proper test kit be used while administering a copper treatment. In the case of Cupramine, the Seachem Multitest kit for copper is the test kit of choice. When using copper, the correct dose must be maintained for the prescribed time. If the level of copper in the hospital tank is too low, the parasite may survive the treatment. If the level of copper is too high, the fish may die from poisoning. It can’t be stressed enough how important the PROPER test kit is for this treatment.

Invertebrates, corals, and microscopic life in the substrate and live rock cannot tolerate any level of copper and should remain in the display tank. They are NOT considered hosts for Amyloodinium and will not facilitate their life cycles.

The second and equally important part of the treatment is the display tank fallow time. Once again, ALL fish must be removed to hospital tanks for treatment and the display tank must be without any fish hosts for a period of eight weeks to ensure that all trophonts have cycled through the free swimming stage and have died off due to a lack of fish hosts.

It is also important to note that the immune system of the fish will be highly compromised. High water quality and good nutrition are extremely important while the fish is in treatment. Ammonia and pH should be monitored closely. Good water quality can be maintained with daily pH-adjusted, pre-medicated water changes. One can also help boost the immune system of the fish by soaking the food in a high quality vitamin supplement such as Selcon or Zoe.

An Ounce of Prevention:

The best measure one can take in the battle against a parasitic outbreak is to keep the organism out of the system in the first place. A proper four-week quarantine period of all new arrivals will help ensure that the system stays “clean”, even if the animals are the initial purchases. This observation period is the perfect time to treat any ailment that may show itself and will ensure that the parasite remains out of the display tank. It’s better to treat in a controlled setting at first, rather than stressing the fish by catching and removing them from the display tank at a later date.

Even though invertebrates, corals, live rock, and other non-fish additions are not hosts for parasitic outbreaks, it is also recommended to isolate and quarantine these items if they come from a system that houses fish life. When items come from a system that houses potential hosts (fish), there is a possibility that a tomont could be transferred into your system from any item within that system.

Marine Velvet is a deadly, difficult ailment to deal with once introduced into a closed system. With the careful selection and proper quarantine of your new pets, you will have, in fact, earned your pound of cure.

Personal experience

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