FRESHWATER VELVET - Piscinoodinium pillulare (also known as oodinium)
Also Information about Costia (Ichtyobodo)



Velvet (Piscinoodinium pillulare) is a flagellate parasite with chloroplasts, while ich is a ciliate, both have similar life cycles, but unlike ich, velvet can use its chloroplasts during dormancy to survive (which is where light can help), but in a full blown infestation, the parasites get their nutrients from the host and are NOT dependent on their chloroplasts.

This is an area of some controversy as some old school methods claim light and salt (sodium chloride) will treat and cure velvet, this has been proven false along with the assumption that this is a parasitic algae (due to having chloroplasts), this is not true. This is a flagellate protozoan.
This parasite is more resistant to higher salt levels than ich (Ichthyophthirius multifilis) and uses the chloroplast to produce nutrients (via chlorophyll and light) when a host is not available or to supplement nutrients derived from the host. It should also be noted that Marine Oodinium parasites do NOT have chloroplasts


What Are These Parasites?

Piscinoodinium pillulare are flagellate protozoa, single-celled organisms that move around by thrashing their whip like flagella. There are many species of flagellates that are part of the normal intestinal fauna of fishes, and many more kinds of free-living flagellates make a living in the mucus of fish gills and skin, without attaching themselves or causing trouble, but even some ordinarily harmless ones can become pathogenic in stressed hosts. Piscinoodinium pillulare is not harmless; it puts down a root like extension and can burrow into the skin or gill tissues. Giardia lamblia is a similar flagellate protozoa in humans that can cause severe acute diarrhea which may lead to a chronic diarrhea and nutritional disorders.

Identification;



Look for fish that scratch or ‘flash’ their bellies in attempts to scrape their gills against stones or gravel.
Rapid respiration or fish that hide or sink to the bottom and clamp their fins, in classic symptoms of malaise. Velvet moves fast, faster than Ich. If you're unwary, you may not realize the fish is being attacked by Velvet until it begins to lose its glossy shine and seems to have patches of yellowish to golden-brown or rusty-colored varnish (which is where the term ‘Velvet’ came from). If you turn out all aquarium and room lights and point a flashlight at the fish, this will make Velvet more visible.

Velvet can also settle out in the gills, where it will send down a root like extension into the gill lamella and dissolves cells then absorbs their contents. This causes extreme gill itch and swelling. In really serious infections, the gill cover may also become swollen. Fish can be killed by Velvet in a few days, either directly from suffocation in the Gills or from secondary bacterial infections.

Treatment:

Copper Sulfate is one of the more effective treatments, as it kills both dormant (destrying the chloroplasts) and kills the free swimming stage as well.
Methylene Blue (this should be used as a medicated bath, buffered with other ingredients, or used in a hospital tank, not as a direct treatment in a display tank) is also very effective and has the added bonus of being a hemoglobin transfer agent for the blood just when the fish need it most.

Acriflavin, and to a slightly lesser extent, malachite green and formalin are also useful. Acriflavin can be used with Copper Sulfate to increase effectiveness without increased stress to the fish

This is why the Medicated Wonder Shells are one of the best treatments for FW velvet.
These medicated blocks contained buffered Copper, Acriflavin and Methylene Blue, three of the better treatments for this infestation along with malachite green. These blocks also add electrolytes and calcium, both essential to good healing.

Another possible treatment choice is Quick Cure, although I have not found this quite as effective for true FW Velvet as it is for Ich.

30 minute, twice daily medicated baths using Methylene Blue and possibly one teaspoon of sodium chloride (salt) per gallon are also very helpful for the treatment of Velvet (and related flagellate parasites as well).
For further information about the use of Methylene Blue, please see this article about chemical treatments: “Aquarium Medications; Chemical Treatments including Methylene Blue”

Back to lighting, this may help with low infestations just like salt does with ich in low infestations, but in a full blown infestation, just like salt it is overrated.
I have witnessed this first hand in my Aquarium maintenance business, even with lights off!

COSTIA

Costia is a single cell microscopic parasite that attacks the skin of fish. It is a flagellate similar to velvet, however without the chloroplasts. It destroys the skin, in mild cases the skin appears cloudy (again similar to Velvet), in severe cases the skin is open and bleeding. It usually attacks fish in a poor state of health or living in poor water conditions or in overcrowded conditions. Secondary bacterial and/or fungal infections can occur at the open sore area. Costia can only survive on fish. Costia usually inhabits the gill and skin and once attached to the host it destroys tissue at that site. Which is why when found in the gill, Costia is so devastating, when present in great numbers Costia will destroy gill tissue.
In very small numbers Costia presents little problem (symptoms for minor infections include sloughed off scales),
however in poor water conditions Costia can kill rapidly.
Costia does do well in temperatures greater than 86 degrees F.

Second picture is of mild Costia infestation with missing scales

Costia is often (and mistakenly blamed on scratching, flashing and similar in fish, however although fish with a Costia infestation may flash/scratch this is not a very clear sign of a Costia infestation and is more likely early symptoms of velvet, ich or simply stress from poor water conditions similar to shimmies (often caused by improper mineral/electrolyte levels).
Luckily, if what one thinks is a Costia infestation is actually Velvet, treatment is similar as above for Velvet (although I have found formalin/malachite green based formulas more effective for Costia and Acriflavin less effective for Costia).

For true Costia infestations, clean water with good parameters (ammonia, nitrites, nitrates, GH, KH) are a MUST. These include the medicated baths, Copper Sulfate, Quick Cure, and Medicated Wonder Shells

For information about aquarium treatments and medications:
AQUARIUM MEDICATIONS, treatments, how they work, and which ones to use and not to use.

Aquarium Ich
For information about Aquarium Ich; Ichthyophthirius multifilis and Cryptocaryon irritans treatment, identification, and life cycle, please visit this site




For information about Saltwater Oodinium (velvet): MARINE OODINIUM (Amyloodinium Ocellatum)

References:
The Skeptical Aquarist-Flagellates

http://www.reefs.org/