THE LIFE CYCLE AND TREATMENT OF "ICH" AND "CRYPT" WHITE SPOT DISEASES
(Ichthyophthiriasis for freshwater white-spot diseases)

(Cryptocaryon for saltwater white-spot diseases)
revised 11/16/07


"Ich" and "Crypt"

The common name for white spot disease, which are single-celled parasites on fresh and saltwater fishes, has for many decades been commonly called "Ich" (pronounced "Ick"), named after its first-described generic name Ichthyophthirius .  Over time it has been established that there are a number of species of white spot disease, both freshwater and marine.  The freshwater species remain in the genus Ichthyophthirius and the marine species are in the genus Cryptocaryon.  As the marine tropical fish hobby has grown in size, the marine species of white spot disease have been referred to by some as "Crypt" after their generic name. 

For the hobbyist as well as the expert fish keeper, it is very difficult to tell the genera and species apart, so the following description is for all species of white spot disease, both fresh and salt water.  The traditional term "Ich" is usually used to refer to both the freshwater and marine species, so the use of the term "Ich" in this article is referring to both "Ich" and "Crypt" diseases. 

Ich white spot disease only attacks fishes, and not other aquatic organisms.  This infection  is one of the most common protozoan (single-celled) infections affecting aquarium and pond fishes.  Fortunately, the little white spots, when on the outside of the fish on the head, body and fins of the fish, make Ich one of the easiest infections to identify from their distinctive tiny white spots.  However, Ich can also be in the mouth, gills, and nostrils of the fish, and be totally out of sight until they spread to the outside of the fish.  Sometimes the out-of-sight infections become so serious that they kill the fish before fish keepers ever realize that Ich has infected their fish. 

The term "Ich" comes from the generic name Ichthyophthirius that applies to freshwater Ich.  The primary freshwater species of Ich white spot disease is multifilis.  The primary marine protozoan causing white spot disease is Cryptocaryon irritans.  However, additional species of Ich are being described, and it is now known that there are multiple species, freshwater and marine, that are infecting fishes. 

The different species of Ich look alike in their little white spots, both in size and shape, but have different lengths of time in their life cycles when they are in the white spot stage.  It is essentially impossible from general observation to know which species of Ich might be involved, and how long they are going to be in the white spot stage.  Therefore, it takes patience in treating fishes for white spot Ich, because it can be weeks to more than a month of daily treatments to get rid of it. -- the amount of time required depending upon which species is attacking the fish. 

Many fish keepers misunderstand what is required in treating Ich white spot disease, and expect to treat for only a few days before the infection will be gone.  But there are two problems in this.  The fish keepers need to realize that the number of times per day and the number of days that there needs to be treatment are critical to success in eradicating this parasite.  Depending upon the species of Ich involved, the number of times per day that the treatment is needed may vary from one to three times per day, spaced out during the day at 24, 12 or 8 hour intervals.  If the species of Ich has a short time period while in the free-swimming stage, and the treatment is made only once per day, the time when it is exposed to treatment can be missed.  If the treatment is not done long enough in the number of days of treatment, the Ich can hatch out days after the treatment period is over and continue to infect the fish.  

The important thing to know is that the only time presently known when treatments are successful against Ich is when the little white spots hatch out.  During the short time that the Ich is in the free swimming stage is the only time that it can be eliminated by treatments.  The different species have different lengths of time in this free-swimming stage, which is generally from a few hours (such as four or five hours or so) to several days (such as usually about eighteen to twenty four hours or more).  Treatments need to be once or more times per day until every last little white spot is gone.  More on this below. 

Diagnosis

The main observable difference between the species of white spot Ich are in the length of time that they are in the white spot stage, which in different species can be for about 4 or 5 days, or about one week, or two weeks, or three weeks, or up to a reported 32 days.   The species with the white spot stage of about 4 or 5 days, or the other extreme of about 32 days are less encountered than those that are one to three weeks in the white spot stage. There is no known treatment for white spot Ich infections when they are in the white spot stage.  Only during the short time of hours up to a few days when they are free swimming can they be eliminated.  Therefore, the parasites in those white spots are impervious to treatments until they hatch out. 

Also, be aware that the fishes can be fatally infected when no white spots are seen on the outside of the fish.  They are infected with the kind of Ich that prefers being totally out of sight inside the mouth, gills and nostrils of the fish.  These Ich are not seen until they venture onto the outside of the fish, which in such cases is often too late to save the fish.  Treatment needs to start as soon as there is the suspicion that Ich white spot disease may be present.  There are reports in the technical literature of Ich that remain in the mouths of fishes throughout all the stages of their life cycle.  So they are never seen on the outside of the fish.

The most common way of diagnosing Ich is by close observation of the infected fishes. It is revealed by the presence of small, (.5 to 1.0 mm) white dots scattered about on the fishes' skin and fins, as well as in the mouth, gills, and nostrils of the fish.  Anywhere the fishes have a body surface - both inside and outside - is where the white spots can be found. 

Seeing white spots on the fishes is not always proof that the fish is infected with ich, as several other infections can have a moderately similar appearance. Proof positive can be obtained by removing one of the spots and observing it under a microscope. The Ich parasite has a small micronucleus and a prominent crescent-shaped macronucleus.

Ich is most often introduced into the aquarium or pond by adding new fishes, snails, sessile invertebrates such as coral or medusae, or aquatic plants.   Ich (in the form of what are called tomites) which have only recently attached themselves to the host are not readily visible.  It is good aquarium and pond keeping practice to isolate any new fishes for at least one month or more under close observation before adding them to a community aquarium or pond.  Also, serious consideration needs to be made for isolating new plant, snail, or sessile invertebrate introductions before placing them in water in which fish are present.

The Life Cycle of Ich and Crypt 

Most fish keepers overlook the fact that there are a number of species of Ich -- how many not yet determined.  Each species varies to some extent in its life history.  There is considerable confusion in the literature on the subject.  The visible stages of Ich are carried out on or in the surface of the host fishes' skin and fins. This first stage or stages of the life cycle which are the most visible to observers are the white spot cysts that are called trophozoites and are highly resistant to drug therapy.   In sufficient numbers they harm the fishes to which they are attached to the extent that they can kill them. 

Trophozoites mature into trophonts and leave the host, normally for most known species of Ich proceeding to the bottom of the aquarium or pond.  These mature trophonts release from 200 to 1,000 "young" for freshwater species called tomites, and up to 250 or more tomites for tropical marine species. These tomites move about looking for a fish host, which they must find, depending upon which species they are, within 4 or 5 hours up to 2 to 3 days at 75° F (24° C) -- the time involved depending upon the Ich species.  If they do not find a new host, most or all will die.  A few may survive by attaching to the surface of an invertebrate or plant, but this happens only exceptionally.  Cooler water temperatures will lengthen the time that the trophonts have to find a host.  It is during this free swimming stage that the Ich are most vulnerable to treatment. 

It is important to note that these intermediate stages may also attach themselves to plants, or onto flat surfaces of aquatic invertebrates (snails, coral, anemones, etc.), and be accidentally introduced into an aquarium or pond along with new plants or invertebrates. Once the tomite attaches to the host, it matures, forms the white spot cyst becoming trophozoites, and the cycle continues anew.


[]


A = The trophozoites in the host's skin.
B = Trophont leaving the host.
C = The mature trophont with hundreds of maturing tomites.
D = The releasing of tomites that penetrate the skin of the host fish. 
A =  The cycle continues all over again.

 

 

 

 

Treatment of Ich

As previously indicated, whatever treatment is used to eliminate Ich has to be effective when the Ich is in its short period of being in its free-swimming stage.  Since it cannot be certain as to when Ich will become free swimming, treatments have to be every day, or twice or more a day for those having a free-swimming stage for only a few hours.
The treatment needs to be harmless to the fish, but effective in killing the Ich's free-swimming stage.

What with new inventions having been made in treating fishes, there is now a choice between using chemical or organic herbal treatments.  Before the choice was limited to chemical treatments, because no organic herbals were known for this purpose.  There are major differences between the chemical and organic treatments, which are outlined under the headings below.

Whether using chemical or organic treatments the procedure for treatment is as follows.  First remove the activated carbon from the water filter during treatment, so that the carbon does not deactivate the treatment. Also, turn off any protein skimmer that is being used in filtration. 

The only time that the white spot Ich can be killed is when it is in the short free-swimming stage of four or more hours up to several days (or more in cold water) after the trophonts emerge from the white spot cysts.  It may be that species of white spot disease (Ich) now being discovered have even a shorter free-swimming stage than about four hours, but this has yet to be confirmed.  What is most common in tropical aquarium keeping is to have about eighteen to twenty four hours for when the trophonts are in the free-swimming stage, and about one to two days for temperate or cold water outdoor ponds. 

If it is intended to shorten the life span of the Ich in the white spots in order to accelerate their hatch rate and shorten the time of the treatment, the water temperature should be increased.  This should not exceed 82-85 degrees Fahrenheit ( 28-30 degrees Celsius) for tropical fishes. When doing this, be sure that there is plenty of aeration in the water so that enough oxygen is present for the fishes' breathing, and that the fish's organs, such as for reproduction, are not harmed.


Organic Herbal Treatments With Organic Herbal Naphthoquinones

These new patented treatments have real advantages, and are highly recommended.  (see Kordon Ich Attack, Prevent Ich, and Rid Fungus, all equally effective against white spot Ich and other single celled protozoan, dinoflagellate, and fungal infections. The organic herbal naphthoquinone treatments are less stressful on the fishes than any chemical treatments.  Multiple treatments per day -- such as one in the morning and one in the evening, or even three times per day -- can be done to be sure that no tomites of white spot Ich get through alive.  No water changes are needed each day during treatment.  A major advantage is that the organic naphthoquinone treatments are not harmful to aquatic invertebrates (shrimp, snails, crabs, sea anemones, coral, star fish, sea urchins, etc.)  

The only concern with the naphthoquinone treatments is that there are some marine corals (Xenia and bubble corals) and sea anemones that may shrink or shrivel up during treatment in obvious reaction to the treatment.  However, in the hundreds of thousands of uses on marine aquariums, there is only one report that any corals died during treatment by the Kordon naphthoquinone treatments.  But it is unknown whether this was caused by the naphthoquinones or not.  There is also one claim that sebae anemones -Heteractis (Radianthus) - released toxins during treatment that killed fishes.  However, this stated by a nonexpert and also has not been corroborated.


[]Using Chemical Treatments
The chemical treatments have a long history of use in treatment for white spot parasites in fish.  The foremost Kordon chemical product for fresh or saltwater fishes is Rid-Ich+ which uses the formula and ingredients developed by professional aquaculture for Ich treatments for commercial food fish.  Other examples of chemical treatments are Kordon Formalin-3 , Malachite Green , Methylene Blue, and Permoxyn (potassium permanganate).  All of these are more stressful to the fish than the organics, so they usually need to be limited to one treatment per day.  For hardiest fishes, it can be two times a day, such as once in the morning, and once in the evening.  A water change needs to be made before each treatment and after the last treatment.  Chemical treatments are toxic to aquatic invertebrates, so should not be used in coral reef aquariums.

The best chemical treatment in the Kordon product line for either fresh or saltwater fishes is Rid-Ich+, followed by Malachite Green. Kordon products that are suitable for use in a separate bath to destroy the tomites of freshwater Ich are Formalin-3, Malachite Green, [hyperlink] Methylene Blue and Permoxyn . For a bath, the fishes must be removed from the original aquarium or pond and placed in a separate aquarium or tank for a treatment time of a minimum of three to four days until after the last observed spots are seen.  The minimum treatment time would be 7-9 days for Ich species with a short cycle of 4-5 days in the white spot stage, but most species are going to require more than two, three, or four weeks of treatment.

All of these chemical treatments can be harmful to invertebrates and some are also harmful to the nitrifying bacteria of the biological filter bed, so appropriate precautions should be taken. Treatment instructions are given under the individual Product Data Sheets for each of the recommended products. Experiments have shown that the use of ultraviolet light (UV) filtration is effective in killing some of the free swimming tomites of freshwater Ich, but some or most of the tomites may remain on the bottom and not be drawn into the UV sterilizer. The minimum lethal dose for the tomites is 100,000 microwatts per second per square meter.

 

How to Avoid Having Your Fish Become Infected With Ich

For new aquarium set ups it is best during the first weeks and preferably to a month or more to do daily treatments with one of Kordon's organic naphthoquinones (Ich Attack, Prevent Ich, or Rid Fungus) to eliminate all single-celled infections that the fish may have.  For additions to the community aquarium or pond with other fishes already present, quarantine new arrivals for one month or more under close observation before introducing them.  The same is true for new ponds for which the pond is too large to treat the entire pond.  In this case use an adequately aerated quarantine tank or children's plastic swimming pool for treating the fish.  During that time treat those quarantined with daily treatments with one of Kordon's organic naphthoquinones (Ich Attack, Prevent Ich, or Rid Fungus) to eliminate all single-celled infections that the fish may have.  See Kordon Article "The Importance of Quarantining New Fish Arrivals Intended For Community Aquariums or Ponds" for further information. 

NOTE: During the breeding season many male freshwater cyprinid fishes, such as carp, goldfish and barbs, will develop small lumps (often with whitish tips) on their gill covers and elsewhere on their heads. These are not signs of a parasite infestation, but a normal manifestation for these fishes



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