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 Post subject: Marine Ich (cryptocaryon irritans) & Marine Velvet(Amyloodin
PostPosted: Sat Feb 25, 2012 1:59 pm 
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Joined: Tue Feb 07, 2012 1:01 pm
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This may be a great deal to read, but it is extremely informative concerning our fish, and the above killer parasites. I hope you take the time to read it.

Thanks to both Mike, and the author Steve Norvich for allowing me to reprint this valuable info!

Marine Ich (cryptocaryon irritans) - the real scoop
By Steve Norvich




Fallow period for cryptocaryon irritans (ich)
A normal distribution is a very important statistical data distribution pattern occurring in many natural phenomena, such as height, longevity of a member of a population e.g. human being.s For this discussion we are focused on the life cycle of Cryptocaryon irritans, otherwise known as marine ich. Certain data, when graphed as a histogram (data on the horizontal axis, amount of data on the vertical axis), creates a bell-shaped curve known as a normal curve, or normal distribution.

Normal distributions are symmetrical with a single central peak at the mean (average) of the data. The shape of the curve is described as bell-shaped with the graph falling off evenly on either side of the mean. Fifty percent of the distribution lies to the left of the mean and fifty percent lies to the right of the mean. The average life cycle of Cryptocaryon irritans is 3 weeks.

The spread of a normal distribution is controlled by the standard deviation. The smaller the standard deviation the more concentrated the data. Unfortunately, there is no published value for the standard deviation of the life cycle of Cryptocaryon irritans.

If you look at the percentages of population members within a standard deviation of the mean, we see that approximately 19.1% of normally distributed data is located between the mean (the peak) and 0.5 standard deviations to the right (or left) of the mean. For Cryptocaryon irritans, we are going to assume that 68% of the members lie within one standard deviation of the mean.

If you add percentages, you will see that approximately:
• 68% of the distribution lies within one standard deviation of the mean.
• 95% of the distribution lies within two standard deviations of the mean.
• 99.7% of the distribution lies within three standard deviations of the mean.

These percentages are known as the "empirical rule". What this means for Cryptocaryon irritans is that leaving a tank fallow for 3 weeks will give you a 68% chance that you have eradicated the parasite, leaving a tank fallow for 6 weeks will give you a 95% chance of eradication, but if you want 99.7% chance, you will leave the tank fallow for 9 weeks. That is the reason you see different numbers being used on Reef Central and in the literature.

I see confusion when different numbers are used for the required fallow period to make sure you tank is ich free. Perhaps this will clarify. Or not!

So what about Marine Ich (cyrptocaryon irritans)?
The life cycle of this parasite is interesting and is important to understand when evaluating a treatment. The stage where the parasite is attached to a fish is called a trophont. The trophont will spend three to seven days (depending on temperature) feeding on the fish and that is what you see symptomatically when you see "salt sprinkled on the fish". After that, the trophont leaves the fish and becomes what is called a protomont. This protomont travels to the substrate and begins to crawl around for usually two to eight hours, but it could go for as long as eighteen hours after it leaves it's fish host. Once the protomont attaches to a surface, it begins to encyst and is now called a tomont. Division inside the cyst into hundreds of daughter parasites, called tomites, begins shortly thereafter. This noninfectious stage can last anywhere from three to twenty-eight days. During this extended period, the parasite cyst is lying in wait for a host. After this period, the tomites hatch and begin swimming around, looking for a fish host. At this point, they are called theronts, and they must find a host within twenty-four hours or die. They prefer to seek out the skin and gill tissue, then transform into trophonts, and begin the process all over again. What this means is that when your tank is infected, you can actually see symptoms during a very small part of the life cycle, and it why your tank is infected even though your fish are resistant. It will also explain why symptoms come and go.

Many hobbyists are fooled into believing they have cured their fish of the parasites, only to find Ich present again on fish a few weeks later; a reason why following through with a full treatment protocol is so important. Don't make this mistake and be lulled into a false sense of security. The parasites may be in a stage where they are merely regrouping and multiplying for their "next offensive." In the wild, this sort of massive reproductive phase ensures that a few will find a suitable host to continue on the cycle. In the close confines of our aquariums, though, it means comparatively massive infection rates.

This disease is usually associated with several environmental triggers. Changes in water temperature, exposure to high levels of ammonia, nitrite, or nitrate, low pH levels, low dissolved oxygen often associated with overcrowding, are all factors contributing to the onset of the disease. You could lump all of these in a general category of "stress", but it is more appropriate to think of all of these as "unnatural conditions". In fact, Cryptocaryon irritans is rare in the wild even more unlikely to be lethal. Ich is truly a disease that exploits the conditions of captivity to reproduce and easily find suitable hosts.

By the way, trophonts are under the skin so cleaner wrasses and cleaner shrimp have no real effect on reducing this parasite.

Treatments which work and Myths and Truths about Marine Ich

Treatments which work:

1. Hyposalinity - Using a refractometer, hold salinity at 11ppt to 12ppt until 4 weeks after the last spot was seen. (Best to use salinity, but if you use specific gravity, that equates to roughly 1.008 to 1.009 sp. gr. units). Raise salinity slowly and observe fish for 4 more weeks. It is difficult to control pH and water quality during treatment, however this is the least stressful treatment for the fish.

2. Copper treatment - Follow medication recommendations. This can be effective in 2 to 4 weeks of treatment. After treatment, remove all copper and observe fish for 4 more weeks. Copper is a poison to the fish and creates some stress.

3.. Transfer method – The fish is moved from tank to tank to separate the fish from the cysts that fall off and the free-swimming stages of the parasite. Two hospital tanks are needed to perform this treatment. The fish is stressed by having to keep moving it between these hospital tanks.

4. These are the ONLY 3 known cures that work almost 100% of the time. Other chemicals will kill the Cryptocaryon irritans parasite, but only in special conditions that are not good for the fish. Some chemicals will only kill some of the organisms, letting the others escape death to go on to multiply and infect.

Observations, Claims, and Common Myths:

1. Some Tangs seem more susceptible. This is true. Their mucous coatings are reduced in thickness and composition.

2. Cryptocaryon irritans goes away on its own. This is definitely NOT true. While Cryptocaryon irritans is only visible at one stage of its life cycle if it was once seen, then it hasn't gone away -- it's just not visible to the aquarist. Reread the life cycle described above.

3. It goes away with a ‘reef-safe’ remedy. This is not true; we all wish it was. This is one of the biggest and most 'dangerous' of the misrepresentations in the hobby. The aquarist thinks everything is okay when it isn't. What usually has happened is that the parasite has killed the fish it is able to kill and the rest have developed a resistance or immunity. The parasite is still in the aquarium, possibly infecting the gills of the fish where it can’t be seen. About 40% of fish seem able to develop this immunity.

4. It was gone then when a new fish is added, it is there again. This is not true. See 3 above. Cryptocaryon irritans wasn’t really gone or the new fish brought in the disease with it. A new addition to an aquarium can be the stress which triggers the other fish to reduce their defense or immunity, this will allow the parasite to 'bloom' to the point where the infection is now again visible to the aquarist.

5. The fish lived through the last outbreak then died during the second or subsequent outbreak. This can be true. The fish had a resistance or immunity that it lost.

6. It was accurately diagnosed as Cryptocaryon irritans, then never showed up again. It wasn’t ich or the fish quickly developed an immediate immunity or resistance, or the fish is still infected in the gills.

7. Cryptocaryon irritans can ‘hang around’ almost unnoticed with just a body spot now and then because it often resides just in the gills. This is true.

8. Aquariums always have Cryptocaryon irritans. This is untrue. Cryptocaryon irritans can be kept out of an aquarium. Just quarantine all fish, rock, sand, sponges, and filter medium and don’t let non-quarantined livestock get into the aquarium.

9. Fish always have Cryptocaryon irritans. Untrue. In the wild fish often show up to a 30% infection rate (or more) but the wild fish survive minor infections. In the tank the parasite can 'bloom' since In the tank the fish can't get away. The combination of bloom and no escape will overcome the fish. In capture and transportation the fish can share the disease and thus many wild caught marine aquarium fishes do have this parasite, but not all.

10. A fish can't be made to be totally rid of Cryptocaryon irritans. Untrue. All marine fish can be cured and rid of any Cryptocaryon irritans infection.

11. Just feed the fish well and/or feed it garlic and it will be okay. Not true. Nutrition, foods, vitamins, etc. don't cure an infected fish. An infected fish is sick and is being tortured by the itching and discomfort. It might pull through and acquire resistance or immunity (see above) but the fish is being stressed by having to contend with a parasite. Don't let this happen to the fish. Cure it!!

12. A new cure has been discovered. Very unlikely. If the aquarist thinks they have found a new cure, then have it researched and independently tested. It's easy and cheap. If it is as good as the above 3 tried and true methods then the professional veterinarians, private and public aquariums, fish farms, and I will use it. The aquarist needs to keep the perspective of how devastating this parasite is not to just the hobby but to the whole fish farming industry. Any new way of 100% treatment will make headlines!

13. If the Cryptocaryon irritans can't always be detected, then why bother with a quarantine procedure? In the confines of a small quarantine and being there for no less than 6 weeks, the Cryptocaryon irritans parasite will make itself known because the fish is weakened and the fish can't get away from being re-infected by multiplying Cryptocaryon irritans parasites. In other words, the quarantine procedure instigates a 'bloom' of the parasite which will make it visible to the aquarist. When this happens, treatment is appropriate with one of the three proven treatments.

14. All white nodules fall off the fish and move on to the cyst stage. Untrue. It has been discovered that, on very rare occasions (we don't know why) the white nodule will encyst and rupture while still on the fish.

15. UV and/or Ozone kills Cryptocaryon irritans. Ozone doesn't kill all parasites that pass through the unit, nor does the water treated with ozone kill the parasites. UV only kills the parasites that pass through the unit. Since the entire water volume does not pass through the unit, not all ich parasites will pass through the unit, so the UV will not rid an aquarium of Cryptocaryon irritans. A UV can help prevent a 'bloom' of the parasites however, and thus help in its control. UV is not a cure nor a preventative measure for Cryptocaryon irritans. When water is shared by multiple tanks, usage of UV can make spreading this parasite from tank to tank significantly less likely.

16. All spots are Cryptocaryon irritans. Untrue. Probably one of the most problematic causes for rumors and “myth-information” in the hobby is assuming that a spot is Cryptocaryon irritans when it may be another parasites or conditions (e.g., pimple-like reaction to infection) that look like Cryptocaryon irritans. The mis-diagnosis is often the cause for claims of what cured Cryptocaryon irritans, when the fish didn't have Cryptocaryon irritans to start with.

17. My LFS quarantines their fishes for 2 weeks and I only buy them to be sure they are healthy and free of Cryptocaryon irritans. Have you been reading the above? First, 2 weeks is not long enough. Secondly most LFS share water among their fish system tanks so if any new arrivals happened, the clock is effectively reset back to zero.
______

Marine Velvet versus Marine Ich

--------------------------------------------------------------------------------

Marine Velvet (Amyloodinium ocellatum) and marine ich (cryptocaryon irritans) are both dinoflagellates with similar life cycles that can affect fish in marine aquaria.

However, marine velvet is much more severe in its impact and is the primary source of tank wipe outs. I see anecdotal discussion attributing tank wipe outs to marineich, but it is much more likely that they are caused by marine velvet.

Here are some differences:

1. Hyposalinity can be used successfully (if done properly) to treat marine ich. However, it has no affect on marine velvet

2. A low level of copper (a non therapeutic dose) has been known to mask marine velvet. That is why LFS or online fish suppliers that run a low level of copper can supply fish with Marine Velvet

3. A fresh water dip has no effect on marine ich, but it does provide temporary relief for marine velvet

4. Fish such as mandarins can often avoid contracting marine ich, however, they can contract marine velvet

Most similarly symptomatic to Brooklynella, Oodinium organisms primarily attack the gills first. At the onset of this infestation fish often scrape up against objects in the aquarium, lethargy sets in, and rapid respiration develops, which is the result of excess mucus in the gills due to the invasion of the parasites. This is typically noticed as fish staying at the surface of the water, or remaining in a position where a steady flow of water is present in the aquarium such as near overflows or powerheads. Fish often become reclusive and hide out of the light

As the disease progresses outwards from the gills, the cysts then become visible on the fins and body. Although these cysts may appear as tiny white dots the size of a grain of salt, like the first sign of Saltwater Ich or White Spot Disease, what sets Oodinium apart from other parasites is that at this point the fish have the appearance of being coated with what looks like a whitish or tan to golden colored, velvet-like film, thus the name Velvet Disease.

Now in the advanced stage of the disease the production of gill and body mucus increases, the fish becomes listless, refuses to eat, and it's not unusual for a secondary infection to develop. For fish that reach this end stage of the disease, it's typically too late. They usually do not respond to treatment, and most often will die. Early in the life cycle, treatment with copper will work or treatment with copper plus formalin dips. (see my blog)

Ich, on the other hand, if visible at all (often it is invisible in the gills) will look like salt sprinkled on the fish (in reality it is under the skin). There are three proven treatment protocols for marine ich: tank transfer, hyposalinity at 1.008/1.009 (test with a calibrated refractometer), copper (test a minimum of daily before lights out).





__________________
Warmest regards and best wishes,

~Steve~


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