So much confusion exists about C. irritans, (also known as: Ich or Ick or SW ich) on the various NG's and discussion boards, and even informational web sites, covering fish diseases, that I am compelled to outline, in as simple language as possible, what is really known and what mythinformation has been disseminated.
Cryptocaryon irritans - a wide spread, ubiquitous, obligate, protozoan parasite.
Found just about in every tropical and even temperate ocean, but mainly associated with coral reef fish. This parasite is specific only to fish, and cannot reproduce without fish being present. It does NOT appear as a result of just stress, but stress plays a role in a fish's susceptibility to it. In the majority of cases, the parasite lodges in the mouth and gills of the fish, remaining undetected, for the most part, and is introduced by a fish. It can also be introduced, in its encapsulated form, as a cyst or cysts, attached to invertebrates, or on LiveRock, or in LiveSand.
What makes this protozoan of interest to scientists, is its unique life cycle. Most protozoans multiply by simple division, one member simply divides its nucleus into two parts (simple mitosis) and then the outside tissue separates into two individuals.
Cryptocaryon irritans, and its FW counterpart, Ichthyophthirius multifilis (where the name Ich comes from) have four stages in their unique life cycle, plus the fact that in its reproductive stage, one individual divides, and can become, into 200, or even more, new parasites. If those 200 survive, they become 40,000 and so on, and so on! This parasite needs to be taken seriously!
Scientifically speaking, its four stages are:
(1) The Tomite - free swimming, highly infective ciliated form (the infectious stage) that measures about 55 x 35 microns, (a micron is one-millionith of a meter). A microscope with at least one-hundred times magnification is required to see this parasite.
(2) The Trophont - Parasitic feeding stage - Once the tomite invades the tissues of its host (fish) it burrows into the fish's flesh, at various sites on the body, including its skin, scales, fins, mouth and gills, and has been known to invade the fish's internal organs. At this stage, the fish secretes a mucous reaction to the feeding parasite, in the form of those ever popular 'white spots' or 'white dots'. Massive invasions in the mouth and gills, can also result in large scale mucous production, which appears as a white film emanating from the fish. Death usually occurs when the fish's breathing apparatus is overwhelmed, or it suffocates from its own mucous production. Massive invasions also make the fish susceptible to secondary bacterial infections as well.
(3) Tomont - Prior to encapsulation, the parasite ceases feeding, and either drops off the fish, or remains in the mouth, gills or internal organs.
(4) Theront - the encapsulated and reproductive stage - The parasite, at this point, can be from 170 to 450 microns in size, and at the larger sizes, can actually be seen by the naked eye. Once encapsulation is completed, its reproductive stage starts, and depending on how well fed the Tomont was, and the tank's temperature, one Theront divides into 2, 2 divide into 4, etc.,etc.,etc., and release, up to and over 200 new infective Tomites!
Summary: You can now see how easily a fish or fishes can be overwhelmed by this parasite, especially in the confines of an aquarium. Its reproductive powers are exponential, and few fish have adequate defenses against it (only fish that secrete large amounts of mucous are able to fend off this parasite).
Treatments: Over the course of many years, the only really successful propagators of marine fish, were public aquariums, with the money and facilities to keep SW tropical fish. These aquariums also employed and attracted biological scientists, chemists and various other disciplines, and where, most of the research and breakthroughs were made, that allowed us, to keep Marine life in the comfort of our homes.
Two basic scourges prevented widespread propagation in the early years, causing epidemics and large scale deaths amongst aquarium fish. One was Amyloodinium sp. a parasitic dinoflagellate (aka Oodinium) or coral reef disease, and the other was Cryptocaryon irritans. (SW Ick)
The only successful treatment known then, was copper, in the form of copper sulfate. The problem with copper sulfate, is that, when applied to a tank with calcerous substances, it attaches itself to minerals in the water and calcites, and quickly looses its effectiveness. Fish have to be treated in bare tanks, and following treatment, the parasite, still in the display aquariums, simply re-infected the fish. A method had to be devised to keep copper in solution, long enough to be effective. The method of keeping copper in solution is called chelation or complexing, where copper is bound to another substance. Following the successful chelation of copper, by scientists working at the Shedd Aquarium, the first really effective anti-protozoan medication could now be applied to display tanks, without fear of loss, for as long as it takes, to rid the tanks of parasites. For the most part, this is still the treatment of choice, especially in display aquariums, where only fish are being kept, utilizing aerobically based biological filtration systems.
The most widely used commercial product, actually coming from the original research at the Shedd, is CopperSafe� by Mardel Laboratories�.
Used according to the manufacturers directions, CopperSafe� is safe and effective when maintained at levels between 2.0ppm and 2.5ppm, for up to 4 weeks, with no adverse effects on aerobically based biological filteration. My own personal use verifies this, over numerous applications.
Another popular copper medication, Cupramine� by Seachem�, has also been widely reported as being safe and effective, when used according to the manufacturer's directions. NOTE: In all cases using copper, several facts have to be noted: It cannot be used with ANY invertebrates, whatsoever. Once introduced into an aquarium, unless all biological materials, substrates and rockwork is replaced, and the tank started anew, Invertebrates cannot be introduced.
Copper also decimates anaerobically based denitrification bacteria, although, used as directed, is harmless towards aerobic bacteria. This means it cannot be used with LiveRock an/or denitrifying sand beds with LiveSand.
My experiences has shown that careful monitoring of copper levels is essential, on a daily basis, for the entire treatment period, for successful eradication, . My personal choice for monitoring CopperSafe� is Kordon's� Chelated Copper Test Kit by Aquatru�
My treatment length recommendation is for 4 weeks. This is followed by a 25% water change, and an additional 25% water change two weeks later. After an additional 2 weeks has passed, all should have returned to normal.
A third and newer treatment, in application, but not in concept, is Hyposalinity. Now, Hyposalinity in various degrees has been used with limited success, in the past. In its newest applications, its been shown to be as effective as copper based treatments. Special considerations have to be made for successful eradication.
Number one: Treatment must be made in a separate aquarium, with aerobically based bio-filteration. FW must be matched for pH and temperature.
Number two: A gradual dilution of SW needs to be done over several days, as not to severely stress the animals. Its recommended that no more then a 25% exchange of FW to SW be done, at any one time, corresponding to a time table covering 12 hours or more. The least stressful way to achieve hyposalinity levels, is the simultaneous draining of SW and filling of FW.
Number three: A final salinity level of 16 ppt or a measured SG of 1.009 at 77�F (calibrated hydrometer) must be maintained for a minimum of 4 weeks. Achieving the correct salinity is critical, as cysts have been known to survive at SG's of 1.011. Followed by a gradual increase to normal levels over as many days, in the same manner, as when hyposalinity was achieved.
Particular attention must also be paid to maintaining pH, as well as the processing of nitrogenous waste products (biological filtration). Periodic water changes may be necessary.
At no time is water from the main tank used during or even after treatment, for a minimum period of six weeks. In fact to insure eradication by attrition, the main tank has to be kept fish free from 6 to 8 weeks, if treatment is done outside the main tank, regardless of methods employed. Even after 6 weeks of attrition, C irritans has been known to have survived!
OTHER TREATMENTS As far as Reef tanks are concerned, there are several treatment options available. However, reports from users has shown that results have been inconsistent and unreliable, with more failures then successes. Kick-Ick� and No-Ick� the two most widely recommended medications for Reef tanks, might be tried when infestations are mild or alternative methods are too difficult or inconvenient, taking into account the risks involved.
A unique treatment was reported by a SW hobbyist, using Melafix� by Aquarium Pharmaceuticals� a patented formulation designated as an anti-bacterial. This hobbyist applied Melafix� Pond Treatment to his tank, based on gross advertised gallonage, at the manufacturer's prescribed dosage per gallon, while raising the tank's temperature to 85�F, for 7 days. This hobbyist livestock consisted of SW fish, such as Tangs and Angelfish, and Invertebrates, such as Crabs, Starfish, Snails, Shrimp, etc. and Ick was cleared up in 7 days. He also discontinued Protein Skimming and Carbon Filtration. His tank was not specifically set up as a 'Reef', but his treatment regimen should be the subject of further investigations, especially with the difficulty (impossibility) of treating a display aquarium with this assortment of life. He also reported no changes in biological filter functions, although he did not have denitrifiction processes operating, to his knowledge, but only aerobically based biological filtration.
Following this treatment, all systems were restored to normal functions and the tank remained disease free. He reported that Ick was introduced with two unquarantined Tangs, further stressing the need for strict quarantine of all newly acquired fish. Still, a treatment worthy of further investigation, in this authors opinion.
Many other, so called 'Reef Safe' medications have proved otherwise, especially those employing the useage of Malachite Green, a bacterial dye, sometimes in conjunction with Formalin, actually a carry-over from FW applications. More often then not, its useage has proven itself a disaster in SW aquarias. Note also that Formalin is a strong anti-bacterial and will destroy biological filters. Reports in NG's and discussion groups have shown some success, especially with very mild cases of Cryptocaryon, in the use of foods soaked with garlic oil. No evidence exists as to its efficacy or the mechanisms involved, or that a 'cure' really happened. Its only useful when fish are still eating, and accept this food. One should remain cautious and skeptical, especially in cases of heavy infestations.
Recommendations made to introduce "cleaners", shrimps or wrasses, as a prophylactic against protozoan parasites, have been widely suggested, despite reports of failures, and studies to the contrary, made by reputable professional aquarists and marine biologists.
The appearance of 'white spots' has led many to confuse the 'symptom' with the disease. Let it be said, in no uncertain terms, that the parasite is MICROSCOPIC and the 'white spots' is NOT the parasite, but mucous secreted by the fish. A poor understanding of this disease, its progression, and symptomology, as led to many erroneous conclusions, doubtful treatment suggestions, and needless fish deaths.
A FINAL WORD I cannot stress too highly the need for a systematic approach in treating fish disease. It should be noted that medications, as in all areas of use, animal or human, must be dealt with some precision and caution, as misdiagnosis, or overdosing is many times more dangerous then the ailment itself. Special considerations has to be given to proper dosage and the correct water capacity of your aquarium. Many aquarists assume that the 'advertised' descriptive capacity of their tank is its 'true' capacity.
NO! A 55 gal Tank does NOT hold 55 gallons of water! And you should NOT be medicating it as if it DID! Its true capacity is critical, especially in the light that the medications most commonly used, are themselves highly toxic, and pose just a big a threat or even more, to the health of our fish.
To get a better idea of your tank's capacity, measure the INSIDE dimensions, especially the height of the water in the tank, going from the top of the substrate, to the water line, plus any displacement by the rockwork. You will find that your tank's TRUE gallonage is something like 70% of its stated capacity.
One more word of caution concerning advise given by your LFS. In my many years of being an aquarist, both FW and SW, most LFS's have NO real knowledge or experience in treating fish diseases, and simply sell you what they have, based on recommendations made by their product wholesale distributors, who have NO experience of ANY kind! Much of the medications that are available, have originally been targeted and tested for Fresh Water fish, and simply relabeled for Salt Water use. I have very grave doubts about claims made as to the efficacy (success) of most medications and even greater doubts as to the research, IF ANY, done by Manufacturers, as to proof of their claims of effectiveness.
I also cannot stress too highly the need to do one's own independent research and study. I have even found the same erroneous statements made by otherwise competent and qualified authors, on the internet, as to facts not in evidence, and mythinformation that has become the 'folklore' of Marine aquarium keeping. The best advice and treatment regimens, is available in many of the established publications and books, where true scientific research was done, and effective treatment regimens were not tied to the endorsement of any one product line. Much helpful information is also lost, when independent useage of novel applications of treatments not specifically recommended, have been reported on various internet newsgroups, interpreted as only anecdotal, and summarily dismissed. Contrary to some so-called 'expert' opinions, every avenue needs to be persued, especially with the difficulties and obstacles presented by 'conventional' treatment regimens. I hope that much of the mythinformation about C. irritans has been dispelled, and this leads to more realistic treatment regimens with fewer fatalities.