Marine Ich (cryptocaryon irritans) - the real scoop

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Cryptocaryon irritans (Marine Ich)

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.

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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.

The truth is out there. . .Trust no one except yourself.