INTRODUCTION

This includes general information about both Ichthyophthirius (freshwater) & Cryptocaryon (saltwater)

Ich, also called white spot disease, is one of the most common protozoan infections affecting aquarium and pond fish. The scientific name for freshwater ich is “Ichthyophthirius multifilis". The marine protozoan causing ich is Cryptocaryon irritans (for more information about Cryptocaryon, please scroll towards the bottom of this article). Both organisms cause whitish spots, called “cysts”, to appear on the bodies and fins of the infested fishes.

As common as this disease is, there is also a lot of misunderstanding and often down right misinformation. Stress is correctly recognized as a major factor in ich infestation outbreaks, however causes of this stress are not always recognized.

Here are a few causes of stress that makes it easier for an ich infestation to take hold (first commonly known stressors):

• Sudden drops in temperature.
• Stress caused by transfer of a fish from one tank to another.
• Stress from other fish chasing or bothering another.
• Stress from high ammonia/nitrites.

• Stress from improper electrolytes (resulting in poor osmoregulation in fish); this is a very important stressor that is easily corrected but often forgotten. For more please see these links:
  Aquarium Chemistry; Proper KH/GH, why Calcium and Electrolytes are important.
  Proper Osmotic Function/Electrolytes
• Stress from poor immunity caused by poor diet and poor Redox.

DIAGNOSIS:

The usual way of diagnosing ich is by close observation of the infected fish.
The presence of small, (.5 to 1.0 mm) white dots (kind of like salt) scattered about on the fishes' skin is an indicator. This is most easily observed around the tail or fins (especially if the fins are normally clear).
You can also check this diagnosis by removing one of the spots and observing it under a microscope. Ich has a small micronucleus and a prominent crescent-shaped macronucleus.

Fish behavior: The fish will often hide in corners near the top of the aquarium to get oxygen, more so as the disease progresses. Sometimes the fish are observed bobbing up and down with their head above the surface, again in an attempt to get extra oxygen as ich infestations often start in the gills and this robs the fish of the ability to properly respirate. Fins are often held down and are clamped as well.

Darting and scratching is also sometimes exhibited (although this is more a symptom of velvet in Fresh water or oodinium infestations in salt water). As the the infestation progresses, the fish become more listless, lose color, and often develop secondary fungal and/or bacterial infections.

LIFE CYCLE:

Ich is most often introduced into the aquarium or pond by adding new fish or aquatic plants. Ich is not air borne.
Tomites which have only recently attached themselves to the host will not be readily visible. It is good aquarium and pond keeping practice to isolate any new fish for at least four days under close observation.

For tropical fish, maintain a temperature of around 75°- 80° F (24° C), depending upon fish kept. Check carefully for the presence of any tell-tale white spots appearing on the skin of the fish and treat them accordingly. If no white spots are observed on tropical fish within four days at this temperature, they can be moved from isolation. Remember, fish maintained at cooler water temperatures, such as pond fish, will require longer isolation times.
The visible stages of Ich are carried out within the host fishes' skin. The first stages are called trophozoites and are highly resistant to drug therapy. Trophozoites mature into trophonts and leave the host, falling to the bottom of the aquarium or pond. These mature trophonts release from 200 to 1,000 tomtits.

These tomites move about looking for a host, which they must find within 2 to 3 days at 75° F (24° C) or they may die. Cooler temperatures will lengthen this time. IT IS THIS FREE SWIMMING STAGE that is most vulnerable to treatment. It is important to note that during these intermediate stages Ich tomites may also attach themselves to plants and be accidentally introduced into an aquarium or pond along with the new plants. Once the tomite attaches to the host, it matures and the cycle begins anew.
The parasite forms a nodule under the skin or gill epithelium of the fish host. It constantly turns and moves under the skin, feeding on destroyed cells and body fluids. It continues to feed on the cells until it matures, causing damage to the skin tissue. This leads to osmotic stress, often resulting in secondary bacterial or fungal infections.
It is this osmotic stress that is often exasperated due to poor aquarium water parameters, in particular low positive mineral ions such as calcium. This is the reason many treatments fail, as osmotic function in the fish is poor and not addressed in treatment/prevention
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How Ich Kills:

The general thought as to how ich kills fish is the epithelium (the top layer of the gill cells) reacts to an Ich invasion by growing thicker, the result of this is a restriction of the oxygen flow from the water to the blood in the gills. The lamellae (respiratory folds of the gills) also become deformed, reducing the proper transfer of oxygen. The shear numbers of Ich trophozoites covering the gills also cause a mechanical blockage of successful oxygen transfer. These conditions combine to stress the fish by hindering respiration.
The epithelial layer of the gill may also separate and cause loss of ESSENTIAL electrolytes, nutrients and fluids from the fish, making it difficult for the infected fish to regulate the water concentration in its body. Bacteria and fungus may also invade the fish more easily while it is stressed from the Ich infection.

Does Ich lay Dormant, or is Ich always Present?

Ich is NOT always present in an aquarium, despite many claims to the contrary which is sometimes used to cover up for poor quality stock.
I have conducted tests (and read others) where I killed off any Ich (if there was any depending on the control group) and then subjected the fish to many stressors that commonly bring on Ich such as sudden temperature drops with NO resulting Ich outbreaks.
It is important to note that the Ich protozoan cannot live outside water and if dried, its cell wall would collapse permanently destroying this single cell parasite so this point also makes migration of Ich from anything other than transport via infected fish or similar water transfer impossible. This also goes for marine Ich (Cryptocaryon) which I almost never had problems with in tanks where all fish were carefully added and there were no previous outbreaks.

Test Method:

*Group 1: I used two aquariums as control aquariums where I started the bio cycle using the fish food method so as to eliminate the slight chance of Ich introduction via a media swap method (one tank was started from empty, the other was bleached prior to start). Fish that had been healthy for many months were used as the control group test fish, and yes this is the weak link, but I feel confident based on baths performed and results that there was no Ich introduction with these fish.

*Group 2: One more tank that was used was already running and I treated it with several treatments of Aquatronics Super Ich Plus (Malachite Green/ Quinine Hydrochloride; this product is no longer available) to kill potential Ich parasites.

*Group 3: Four more established aquariums were used where no pre-treatment was used but had ich at a previous time and had been chemically treated, one a mild treatment with Kordon Rid Ich and the other three with Super Ich Plus.

*Group 4: Was a tank that was also established with no pre-treatment but also had a previous Ich infestation that was treated via the heat method

After subjecting these tanks to stressors that included in ALL tanks a drop in temperature from 78 F to 68 F AND heavy bio load stressor fish food and filter removal so as to spike ammonia (approximately 2-3 ppm if my memory serves me correctly, as I did not write this number down);

*Group 1; No Ich outbreaks
*Group 2; No Ich outbreaks
*Group 3; One outbreak in one of the Super Ich groups (none in the other two) and a major outbreak in the Rid Ich group
*Group 4; A minor outbreak of Ich

Before any reader of this rushes out and purchases Super Ich Plus, it is no longer available, however “Sea Chem ParaGuard” and the older “Quick Cure” are comparable products (ParaGuard being my favorite now due to lower side effects on sensitive fish). I also did not use Medicated Wonder Shells in this experiment, but based on subjective use I would expect good results.

I have no firm evidence of how Ich can lie dormant, my anecdotal thoughts here are that the trophozoites (which are the most drug resistant, except for bleach, bare tank) can somehow lie dormant until conditions are right, where as the tomtit stage cannot live more than a few days without a host.

PREVENTION:

As in many parasite caused fish diseases the fish may need to be stressed due to changes in environment, poor water conditions, and/or stress from other fish to be susceptible to the parasite (this is not to say a perfectly healthy fish cannot get ich, only that often a foothold in a stressed fish is the starting point). Also, the parasites must be present in the aquatic environment (ich is not air borne).
It is not unusual for an aquarium population to have a low level of ich infestation present but not be showing any signs of the disease. Then, once a new fish is placed into the system or a weak/stressed fish becomes the start point for an ich infestation gets a foot hold in the aquarium. Fish can sometimes carry the parasite and not actually be diseased. These carriers can shed the parasite into a new aquarium into which it is placed. If the fish in the new aquarium have never been exposed to the parasite, and they become stressed, they can develop the disease.
Put another way, with healthy fish, they can usually produce enough mucous to prevent the ich tomites from getting started on the fish, but once these tomites get a foot hold on a stressed fish, even the healthy fish get overwhelmed.

The health of an aquatic environment can play a major role in susceptibility to the ich parasites. High ammonia and nitrites severely stress a fish. Also long term nitrates above 50 ppm in freshwater or 30 ppm in saltwater can weaken the immune system in fish.
Calcium is also often forgotten as an essential to fish health (including soft water fish such as Discus). Without calcium, fish cannot carry out many osmotic functions and are more susceptible to disease, including ich infestations. In fact I have found much quicker response to treatment when adequate calcium is present in freshwater aquariums.
For more information about Calcium and KH, please see this article:
CALCIUM, MAGNESIUM, GH & KH IN AQUARIUMS

A healthy, cycled aquarium (0 ammonia/nitrites; low nitrates) with a steady temperature and a GH above 100 ppm WITH constant positive mineral ion replenishment is less likely to develop ich, or when it does, a healthy aquarium will have a less serious and more easily treatable infestation.
High DOC (dissolved organic compounds) can allow for a more serious infestation and hinder treatment by creating a less stable environment as to KH, pH, and poor Redox Balance, so a clean aquarium with little organic aquarium as well as good circulation is essential.

Before you begin any treatment, make sure your water parameters are correct, otherwise this may just worsen the situation and make treatments ineffective and/or poisonous:
*Ammonia- 0
*Nitrites- 0
*kH- 80 ppm or higher (depending on fish, marine much higher)
*GH – 100 ppm or higher (again depending upon fish kept) for important mineral ions (electrolytes) along with constant mineral cation replenishment necessary during times of stress, especially an ich infestation

If you are having problems with ammonia, Prime is an excellent product for de-toxification of ammonia and nitrites. Prime only changes the electron number in ammonia (NH4 to NH3) making ammonia less toxic, but ammonia will still show in ammonia tests (except with the SeaChem Ammonia Alert).

Changing 20% of your water before treatments is also helpful in an effective treatment.

I strongly recommend reading this article for a more in depth discussion of Disease Prevention (which includes Ich):
“Aquarium Disease Prevention”

TREATMENT

I will cover several different treatment methods, and although I may seem to promote one over another, I would like to stress that many experienced aquarists will have a method that works best for them and their types of fish.
What I do want to stress is often many aquarium keepers will make statements that one method will not work or that their method is best when in fact not all conditions are equal (apples to apples, not apples to oranges).
What I am getting at is, if for example your aquarium has high DOC, is acidic and has poor mineral levels, your treatment with medications such as Malachite Green will likely not do well.
By the same token, the heat method is not a good choice for a tank with poor circulation, a high bio load, and especially with heat sensitive fish. While under the right conditions (especially with many heat tolerant South American Species) the heat method may be your best choice.

I have performed MANY true scientific tests (which involved control groups and testing each method under the SAME conditions), so my results and comments below are based on these tests, not anecdotal results from different aquariums.

It is also important to note that regardless of which treatment method you choose, the temperature of the aquarium or pond will effect the outcome since the ich lifecycle is sped up by warmer temperatures, which is why even if medications are used it is often a good idea to bring up the temperature at least a few degrees (say to 80 F) even if you are not using the “heat method”.

Another important note regardless of method used, is to treat long enough to kill the FULL lifestyle of the Parasite. Even many of the effective treatments will often need to be treated for at least 10-14 days (sometimes everyday with small water changes before each treatment). This where “Medicated Wonder Shells” shine in that although they are not the strongest medicated treatment, they are great for follow up after using a stronger medication such as Quick Cure.
Even with the heat method and other non medication treatment, please keep in mind the life cycle of Ich and keep the treatment going long enough to break the life cycle, not just get rid of the “White Spot”.

Finally, I will state ANY method will be more effective if your water parameters are the best that they can be, which includes ammonia, nitrites, nitrates, and even GH. This is for important calcium, magnesium, and other minerals necessary for correct osmoregulation of the fish. Good circulation and filtration are also important as well.

Medication Treatments:

There are many ways to treat ich infestations in freshwater, less in saltwater, but not all treatments are equal or can be used for all types of fish or all aquatic environments. I will discuss the medication options I prefer to use in my maintenance business or in my personal aquariums first.

Also many anecdotal aquarium keepers will comment that "Malachite Green killed their fish", when in reality it was how they used this chemical/product in low ph and under mineralized water and then falsely blame the medication.
This is a VERY important aspect that is often forgotten or unknown; Malachite Green is much more toxic at lower pH (especially on the acid side of the pH algorithm). Calcium is VERY important to buffer this. Calcium also improves osmoregulation further lowering Malachite Green toxicity and improving effectiveness. See this article:
“Calcium, GH, KH, & Electrolytes”.

Although there are methods of Ich treatment that do not require traditional medications (such as heat, salt, even pepper), I recommend a quality Aquarium Ich medication if the infestation is moderate to severe (especially severe), if you are too busy to check your tank a few times per day (as the other methods such as heat takes better monitoring), and/or if your tank has a high bio load and low dissolved oxygen.
As noted in the previous sections of this article, low DOC (dissolved organic compounds), good circulation/bio filtration, proper mineralization (such as Calcium), make a big difference in effectiveness of ANY treatment.

For freshwater, a Malachite Green/ Formalin combination has generally been the most effective for moderate to severe infestations. “Quick Cure” is a good product with this combination of medications (Malachite Green/ Formalin), and from my test is probably the strongest with a wider range of parasites treated as well.
However in most instances, a newer product: “Sea Chem ParaGuard” is safer and more tests are showing this product to be almost as effective a treatment for moderate to severe Ich infestations as Quick Cure, with little side effects when used properly (it can be combined with a Medicated Wonder Shell at ¼ to ½ dose as well, but caution should be used when such a combination is performed).

Malachite Green by itself as in “Nox Ich” is also effective in moderate infestations.
Other medications that can work for freshwater Ich include Copper Sulfate as found in “Mardel Copper Safe”, Quinine Sulfate or Hydrochloride and products that contain Acriflavin (although Acriflavin is a mild Ich treatment and is better suited to Velvet and Fungal treatments).

For Scale-less or Delicate Fish, use Malachite Green at a quarter to half dose along with Triple Sulfa. The safest treatment for scale-less fish is Quinine Hydrochloride, but this is less effective than other medication treatments, although it can be combined with half or quarter strength Malachite Green for more effectiveness.
Another point as to Triple Sulfa is, even with less sensitive fish such as Goldfish; the use of Triple Sulfa still buffers the harsh effects of Malachite Green and more importantly for fish that are not that sensitive to Malachite Green and are kept in a healthy KH and properly mineralized aquarium (the use of Regular Wonder shells are great for the mineral cations necessary for buffering and disease prevention) the use of Triple Sulfa is excellent for fin damage that is a common secondary infection with Ich outbreaks!

With sensitive fish (such as Clown Loaches) it is imperative that you are careful with most ich treatments. Malachite Green is more dangerous to these fish, however if used in a buffered form such as ParaGuard or Medicated Wonder Shells it is less toxic.
As noted earlier, you may also use Triple Sulfa at the same time to further buffer the Malachite Green. I and many of my colleagues have used this method considerably for Clown Loaches, Elephant Nose, etc. with good results and this is my preferred method for moderate to severe ich infestations involving scaleless fish such Ghost Knives or Elephant Nose.

It is also noteworthy that Triple Sulfa tends to be the best treatment for Septicemia, which commonly follows serious Ich infections, especially in Anabantidae Family of fish (which includes Gouramis, Paradise Fish, Bettas); so treatment with Triple Sulfa, even before treatment of Ich is finished, may be advised.

Treatment Duration, Follow-Up: Any of these treatments should be followed for 10-14 days (with small 10-20% water changes if at all possible between each treatment). A Medicated Wonder Shell can be used for a week or two instead of stronger medications once the main infestation has cleared, but a follow up treatment is still required.

It should be noted that sodium chloride (salt) can be combined with all these recommended treatments at a rate of 1 teaspoon per gallon for many fish and 1 tablespoon per 5 gallons for more salt sensitive fish such as Catfish, Tetras, Clown Loaches. This will help most all medications be more effective, in part by adding electrolytes that improve the “slime coat” so as to help fish naturally resist Ich.
For further information about the use and safety of salt in freshwater aquariums, please see this article: “Salt in Freshwater Aquariums”.

Malachite Green is generally safe (so long as it is zinc free) for shrimp, crabs, & snails. Be careful with Copper, and prolonged exposure to Methylene Blue. Please see this article for more in depth medication information: "Aquarium Medications and Treatments; How they work"

For severe infections (especially with sensitive fish such as Clown Loaches) I would recommend a bath in Methylene Blue for as many fish as I could capture, especially the really sick fish that tend die quicker from ich such as Clown Loaches again. This bath will also help with the main reason ich kills (in my experience), depletion of oxygen from damage to the gills.

Methylene blue is a hemoglobin transfer agent. To prepare this bath I use 1 teaspoon 2.303% solution per 5 gallons in a bath of aquarium water from the tank the fish you wish to treat came from, I usually use about a ½ gallon of water, however you may use less. I also recommend about one teaspoon of salt (Sodium Chloride) per gallon of dip water to aid further in aiding the fish via production of more mucous, and yes Clown Loaches CAN tolerate some salt, just not a lot. Please reference this article for research proving this: “Salt in Freshwater Aquariums”).
Measurement of the Methylene Blue does not need to be precise as this bath should be used for about 30 minutes. Make sure you keep the water in a warm area, as in a cold room the water temperature can drop rapidly which would stress the fish. Do NOT pour this water back into your display aquarium when finished. This can be performed twice per day. After this bath I would also suggest a 3 minute dip for most dire of fish in a salt solution of about 1.012 specific gravity, this will rupture some of the Trophozoites on the fish.

For further, more in depth information about highly recommended fish baths (for moderate to severe ich infestations), please read this article: Fish Baths/Dips for supplemental of parasite infestations

For mild to moderate infestations I also use “Medicated Wonder Shells” as these products have Malachite Green (lower levels safe for most delicate fish), Acriflavin, and small amounts of methylene blue (not enough to affect bio filtration) and copper. What is best about these Medicated Wonder Shells is that they also add electrolytes, calcium and maintain a proper GH, which is very important for treatment with Malachite Green as this medication is more toxic at lower pH and in low GH/Calcium levels.
Medicated Wonder Shells are great for use in tanks with poor or no filtration such as many betta tanks, for office or other aquariums that cannot be monitored, tanks that are low in calcium, or in cases for aquariums that have new fish or past Ich problems as a preventative.
As well, a Medicated Wonder Shell can be combined with a ¼ to ½ does of a stronger Ich medication such as ParaGuard for a more even medication delivery as well as the mineral cations that the Wonder Shell provides.

One more treatment option is a hospital tank with a Sponge Filter and no gravel. Methylene Blue works well here, but so do ALL of the above treatments.

A false assumption by armchair aquarists is the dangers of ich medications such as malachite green. Yes this is a poison and can be more poisonous to scale-less fish, but many of these persons do not recognize the importance GH, KH and pH play in the treatment and toxicity of ich medications such as malachite green. (Usually the pH or GH was too low and the medication gets blamed for poor water parameters) At a GH below 100 ppm, you have too low of calcium and other essential electrolytes to aid in osmoregulation which is SO VERY important as to natural resistance to ich infestations. GH buffering is why the Medicated Wonder Shells are especially useful for delicate fish. Also a KH of at least 50 ppm will help to buffer the pH (which buffers the malachite green itself). More should be read about the role KH, GH & Calcium plays even in soft water fish in my article: How to maintain a Proper KH, why calcium and electrolytes are important.
For more information about chemical ich treatments; their strengths and weaknesses, as well as debunking of some more myths, please read this article:
Aquarium Treatments; Parasite and chemical treatments

I will also note to the many different treatments currently available; many are similar Malachite Green/Formalin combinations, however not all are equal. One often recommended product is Rid Ich, which is very safe however in the MANY tests of this product it usually fails in moderate to severe infections so unless your fish are strong, the water conditions are good, the disease is mild or you have very sensitive fish such as Ghost Knives, I would not recommend this product.

Here is a quick review of two other potential chemical treatments for Freshwater Ich:
*Kordon Rid Ich; Very safe, but often poor effectiveness for moderate to severe infestations.
*Tetra/Jungle Ick Guard; reasonably safe product when proper water chemistry is kept, good effectiveness for mild infestations, only fair effectiveness for moderate to severe infestations.

Other freshwater Ich treatment methods; Salt Method

Another method that can work is salt, possibly combined with heat. 1-3 teaspoons of salt is added per gallon of tank water added SLOWLY over 1-2 days (while watching fish' reaction) and the temperature is adjusted to 84-86 F. If this method is chosen you can use plain “Aquarium Salt” which is simply sodium chloride, water softener salt, or even marine salt (which is good for many freshwater fish due to other essential minerals, the exception might be the use with soft water preferring fish such as those from the Amazon Basin or SE Asia). You need to add the salt slowly, watching for adverse reactions, especially with Catfish, loaches, and similar (I do not recommend this method with Elephant Nose, Ghost Knives or similar fish that use electrical signals for navigation). Continue treatment until ALL spots are gone and the CONTINUE treatment for another 3-5 days past this point.

I have tested many methods over the years, and I believe many aquarists use this method more under the assumption that is safer and even more effective when often it is neither (although under certain conditions with certain fish/invertebrates it can be safer).
Salt is safe for most fish, but some fish such as elephant nose, Ghost Knives, as well as many catfish, Clown Loaches, etc. are salt sensitive (not as much as Elephant Nose) so I would be careful and not go past 2 teaspoons per gallon.
Also this method can take so long that the fish die of the ich infestation (I have affected a cure with salt, but is generally less effective, and research bears this out).

However for serious ich infestations, salt by itself is often not enough. Under good water parameters and good circulation I will admit that I have achieved good results with the salt method for mild to moderate ich infestation, however even then, in head to head controlled tests under the same conditions, medications such as ParaGuard always worked faster with no side effects (especially when used with Triple Sulfa) when compared to salt. I will also note as to salt treatments for ich infestations, I am not trying to knock this method for treatment among many more advanced aquarists, however I have seen many novices fail with this method more often than the medication methods.
My opinion as to why this happens is that most do not have the proper circulation needed, most also wait until the last minute when the salt method is even less effective, and often many just do not have the time to monitor conditions (which is where the Medicated Wonder Shells shine), and often this all boils down to an earlier point of mine and that is all things equal, my tests with the salt method come up short as compared to products such as ParaGuard or Quick Cure.

It should also be noted that water with a higher salt content does not hold as much dissolved oxygen, so good circulation is important (as it is with any ich treatment).

For my article about how salt works in freshwater, please see this article: Salt use in Freshwater Aquariums

Heat Only Method

This method is based on the theory (& study) that Ich cannot reproduce in temperatures over 85 F (30 C). This should be performed slowly at a rate no higher than 1-2 degrees Fahrenheit and proved ample circulation and filtration (such as air Stones and power heads). This method is often employed with the salt method, which often confuses many aquarists as to which method truly worked. I do recommend this method over the salt method for Elephant Nose, Ghost Knives (& similar fish that use electrical signals for under water navigation), as well as fish such as Discus and other cichlids, or other fish that tolerate high temperatures well. In general I have found better results with the pure heat method over the pure salt method.
As with the salt method, you need to maintain the high temperatures at least 3-5 days beyond the disappearance of the last white spots.
Due to very low oxygen levels in higher temperature aquariums, one should not combine this method with any chemical treatments which will often further deplete oxygen.
Please note that dissolved oxygen greatly DECREASES at temperatures about 80 F (27 C), many fish are sensitive to this, especially fish from more salty or alkaline waters. You need to maintain a dissolved oxygen level between 5-7 ppm, under 3 ppm can be dangerous, especially with an ich infestation.

This method has its flaws and again is often over rated based on false assumptions. One problem is that this method takes a lot of initial monitoring as temperatures are increased, which many busy aquarists cannot spare the time for, also in moderate to severe infestations the fish already have severely depleted blood oxygen levels due to the ich infestation and raising of the aquarium temperature can be the final nail in the coffin. I have found this especially true with fish that do not tolerate heat as well (such as many North American fish or other fish that naturally come from cooler waters).
In my tests with the heat method (mostly in the 1980s and 1990s when I had access to multiple aquariums in my maintenance business), I also found a higher incidence of Ich return with the heat method over the other ich treatments (used correctly WITH proper water parameters).

Another false assumption is that this method is safer than chemical treatments, as I just noted in my previous point this is not true, and the assumption of the dangers of medication is often based on misuse, the use of poor ich remedies, or poor water parameters such as calcium/pH levels which has an effect on many medications and the ich itself. This said, this method CAN BE a safe alternative to medications (as I am not trying to over sell the use of medications as often medications are over used in aquariums when changes in environment are more important) if you have the time, have fish that in particular respond well in high temperatures, or the infestation is low to possibly moderate.

My use and that of my colleagues in the aquarium maintenance business is fairly limited as to positive results with these types of ich treatments, however that is not to say that they cannot work and continued improvements by the makers of these products may yield more positive results in the future, so experimenting with these treatments for mild infestation may be worth your time.

One such treatment is Kordon’s Herbal Ich Attack which uses active ingredients consisting of five natural organic herbals, based on their containing patented naphthoquinones which are naturally occurring colored substances derived from phenylpropanoid and isoprenoid precursorsin plants.
Of the organic treatments, Kordon’s Herbal Ich Attack has shown results almost comparable to many chemical treatments.
The known effects of the naphthoquinones on parasites/fungus/bacterium also bode well for this treatment. However the poor activity of naphthoquinones on gram negative bacterium limits their aquatic use for this area of treatment, also naphthoquinones show activity against aerobic gram positive bacteria indicates some harm to biological filter beds can occur.
Another positive is that pH is not an issue as with Malachite Green or similar chemical formulas, however it is still highly advisable to maintain adequate KH and especially proper mineral ions if only as an aid to natural immune response.

See this article for more about naphthoquinones:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16553949

Another organic treatment method is the use of hot or black peppers for the treatment of ich in fresh and salt water. Kent Marine makes RXP Parasite Treatment which contains pepper in an easily dissipated treatment solution. Mine and others limited use of this product have yielded mixed results (the claims by the manufacturer are a bit over blown in my opinion), however in mild infestation this may be a treatment worth trying. It is also worth noting that Kent Marine may improve this remedy, so later versions may improve.

Finally another organic Ich remedy that I have tried, again with mixed results (but with results similar to Metronidazole) is Usnea (please follow the link for more information about Usnea) which is a lichen that is brewed like a tea and then added to an aquarium on a daily basis or as necessary to achieve desired results.