Aquarium Ich Disease | Ichthyophthirius Multifilis & Cryptocaryon
Treatment, Identification, and Life Cycle.
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By Carl Strohmeyer-PAMR 35+ years experience
This includes general information about both Ichthyophthirius (freshwater) & Cryptocaryon (saltwater)
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):
Equally important stressors that are often forgotten:
Please read on for more in depth information on freshwater and saltwater Ich that is gathered from current research AND years on controlled studies on my part.
The usual way of diagnosing ich is by close observation of the infected fish.
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.
Ich is most often introduced into the aquarium or pond by adding new fish or aquatic plants. Ich is not air borne.
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.
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.
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.
How Ich Kills:
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.
Another key point is a common way to treat Ich, in particular Marine Ich (Cryptocaryon) is to leave an aquarium without fish for 6-8 weeks since it will eventually die out and is ONLY introduced to aquariums.
SeaChem Tech support also points this out:
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);
“SeaChem ParaGuard” and the stronger "Super Ich Plus" are comparable products (ParaGuard being slightly safer for delicate fish while the AAP Super Ich Plus is stronger and is generally the better choice). 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.Back To Top
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.
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 40-50 ppm in freshwater or 30 ppm in saltwater can weaken the immune system in fish.
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.
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.
Use of a Medicated Wonder Shell is also advised when new fish are added for 10-14 days. If shrimp or other invertebrates are present, the Marine Medicated Wonder Shells which do not have copper can be used (however these are not as effective too).
I strongly recommend reading this article for a more in depth discussion of Disease Prevention (which includes Ich prevention, quarantine, baths, etc.):
Here is a specific Fish Bath reference article:
FIRST, before any aquarium Ich treatment it is important to know all the steps as often treatment is much more than dumping medication, adding salt, or turning up the heat in an aquarium as has already been outlined in this article.
I will now 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.
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”. However, be careful not to combine too many different methods thinking one way is good, 2 o 3 combined methods are best, as an example raising the temperature to 86F can emphasize the side affects of many chemical and even organic treatments.
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.
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.
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.
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.
For freshwater, a Malachite Green/Formalin or Malachite Green/Quinine Hydrochloride combination are generally the most effective for moderate to severe infestations.
However in many instances, another product: “AAP/SeaChem ParaGuard” is safer for sensitive fish such as Loaches or Cory Cats and my tests are showing ParaGuard to be a reasonably effective a treatment for moderate to severe Ich infestations, with little side effects when used properly.
As a side note, the manufacturer of Quick Cure was purchased by Sergeant Pet Products, who promptly discontinued Quick Cure, Clout and other product made/sold by the original manufacturer. Fritz has now bought out the license for Quick Cure, but then later discontinued the product.
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 “SeaChem Cupramine”, 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 but it does work reasonably well with less toxicity for delicate fih when combine with Malachite Green.
For Scale-less or Delicate Fish, use Malachite Green at a quarter to half dose along with Triple Sulfa at full strength. 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.
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.
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 reference this article:
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.
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 bath water to further aid the fish via production of more mucous, and yes Clown Loaches CAN tolerate some salt, just not a lot.
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.
Finally, due not confuse this bath with a preventative bath that should also contain ParaGuard or Metronidazole at full strength in addition to the Methylene Blue.
For further, more in depth information about highly recommended fish baths (for moderate to severe ich infestations), please read this article:
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.
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.
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.
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.
For more information about chemical ich treatments; their strengths and weaknesses, as well as debunking of some more myths, please read this article:
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:
Other freshwater Ich treatment methods; Salt Method
Another method that can work is salt, possibly combined with heat.
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).
However for serious ich infestations, salt by itself is often not enough.
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 AAP Super Ich Plus or ParaGuard when used in the correct water parameters that INCLUDE constant replenishment of mineral Cations!!
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 follow this link:
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.
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!
This method has its flaws and again is often over-rated based on false assumptions.
A common flaw with the Heat method is that a opportunistic Columnaris infection may follow, since Columnaris is MUCH more virulent at higher temperatures, and with already weak fish, the heat then provides an open invitation for this disease!
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.
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.
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 as well as some harm to biological filter beds can occur.
Product Resource: Herbal Ich Attach at AAP
See this article for more about naphthoquinones:
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 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.
Here are a few truths and myths about FW ich (ick) treatments:
For information about FRESHWATER VELVET (Piscinoodinium pillulare), As well as Costia (Ichtyobodo) follow this link (this article is from Aquarium Answers)
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FOR SALTWATER CRYPTOCARYON;
Often I first Start with a Freshwater Dip (when possible)
This dip does not destroy Cryptocaryon in the water column of the aquarium but at least removes the infestation on the fish while other methods can be employed in the aquarium.
Despite some anecdotal comments I have read in a few forums, while a "dip" may be stressful, I have yet to loose a marine fish in 100s if not 1000s of freshwater dips of marine fish assuming the fish was not already "on its way out". Often even fish that were lying on the bottom with a Cryptocaryon or Oodinium infection would perk up after the dip.
Where I would not consider a dip worth the time is if you have a Reef Aquarium with many prize corals, clams, anemones, etc. and chasing around a few Percula Clowns is simply not worth the trouble and potential destruction of your "reef".
A low salinity of 1.009 specific gravity causes the most of the Cryptocaryon tomonts to rupture, killing them. This is the method that I have used in the past with so-so results, HOWEVER I found that I was not lowering the specific gravity (salinity) enough as I only lowered the specific gravity to 1.015, which I later found to be too high to work correctly.
'Higher' boney marine fish maintain their osmotic concentration at about one quarter to one third that of sea water.
When fish are under stress, one of the processes that is affected is ion regulation. This means they have difficulty adjusting the concentration of ions such as sodium, chloride, etc. Lowering the salinity of the tank water makes the concentration of ions closer to that of the fish internal fluids and reduces the fish efforts to maintain the correct concentrations.
This method is best carried out in a separate tank if sharks, ray, or any other invertebrates are present as Sharks and rays may not survive hyposalinity due to their unique method of osmoregulation. They have similar concentrations of salts to higher boney fish however, they also have very high concentrations of organic compounds which give their internal fluids the same osmotic concentration as sea water.
If you have a fish only or a FOWLR tank you may treat with this method in the display tank, keeping in mind that any copepods or other invertebrate life forms living in the live rock may be killed by this method, however the bacteria in the live rock will survive and you may save some of these life forms in the live rock by moving some of these life forms along with selected live rock to a separate holding aquarium during this treatment.
For best results, this method should be employed for 4-6 week period (although some have reported success in half this time). It is VERY important that pH and alkalinity be monitored during this period and maintained to prevent additional stress.
You should enter this hyposalinity treatment slowly from your specific gravity of 1.019 -1.025 to 1.009 over a 48 hour period using RO/DI or even de-chlorinated tap water and/or water changes using low salt water mixes (such as 1.005 salt mixes).
Product Resource: Marine Buffer for Carbonates and Minerals, Alkalinity
When treatment is finished the fish should be returned via high salt mix water changes (such as a water change with a specific gravity of 1.030) over an even longer period of 72 hours.
Copper is still the most effective medication for treatment of Marine Ich/Cryptocaryon I have found for moderate to serious infestations.
Unfortunately it is NOT AT ALL SAFE for ANY invertebrate and removing most of the more effective copper treatments such as Mardel CopperSafe is often difficult from tanks with coral sand, rock, etc. since these copper solutions are readily absorbed and then slowly leech out. This results in the aquarium keeper's inability to add back delicate invertebrates for some time after finishing treatment (often months).
Malachite Green is relatively safe for saltwater fish, FOWLR tanks, and some invertebrates such as crabs and even some anemones, but definitely NOT for cephalopods.
There is a marine version of the “Medicated Wonder Shells” which only contains Malachite Green, this product is only mildly effective for marine ich (Cryptocaryon) depending on conditions and whether other remedies such as dips also being employed (which cannot increase effectiveness. Combining with a 1/2 dose of AAP Greenex can increase effectiveness
Quinine Sulfate or Hydrochloride is also relatively safe for most fish, but not most invertebrates when used at therapeutic doses by itself (combined with Malachite Green it can be safer while still reasonably effective).
Similar to the Quinine Hydrochloride is Chloroquine Phosphate, which is made more effective when combined with Pyrimethamine as found in the product AAP Marex.
Product Resource: AAP Marex Oodinium/Brooklynella Treatment
An organic treatment that again has shown some effectiveness is Kordon’s Herbal Ich Attack which uses patented organic naphthoquinones.
An alternative treatment that we are currently experimenting with, so I admit some skepticism (but I have found few reliable reviews) is a product called “No More Sick Fish”. This product is quite pricey, but also requires small treatment doses. Some tests do confirm relative safety to corals such as Xenia.
The use of a hospital/quarantine tank is still the most effective and safe way to treat a Cryptocaryon infestation. I recommend using a seasoned “Sponge Filter that is kept somewhere in your main display tank, ready for use if the need arises or with a continuously running quarantine tank. If kept in a main tank Sponge Filters will not raise nitrates if properly rinsed on regular basis.
In your quarantine tank, copper sulfate kept at 20-25 ppm (a Copper test kit is recommended when copper is employed for Cryptocaryon treatment) is still the most effective way to treat in Cryptocaryon saltwater, but copper (especially chelated) can be hard to remove from your system once used and is deadly to invertebrates. I personally only recommend treating with copper in an isolation/quarantine tank except in relatively simple fish ONLY tanks.
Other excellent options in a quarantine tank include Sea Chem ParaGuard, Medicated Wonder Shells as well as many other similar products.
For saltwater fish, prevention is still the best cure.
A quarantine tank for new fish and/or hospital tank for sick fish are also beneficial.
Keeping your tank slightly on the hypo-salinity side at 1.019- 1.021 will also somewhat lessen the chance of Cryptocaryon and aid in treatment or prevention as well. However this is more effective for Oodinium prevention and treatment than with Cryptocaryon unless copper is also added at 25 ppm to this quarantine tank.
The Hyposalinty method is also very useful as a means of prevention by treating new arrival this way generally in a quarantine tank in either partial Hyposalinity such as 1.015 (Along with other methods such as Methylene Blue and Copper Sulfate/Formalin) or full Hyposalinity of 1.009. This method can also be used for new arrivals in the display tank assuming no invertebrates or rays/sharks are present and you follow correct acclimation procedures.
In a dip, I adjust pH (so as reduce more osmotic stress than need be) and add Methylene Blue (at double in recommended tank strength as per the bottle). I will use a specific gravity of 1.001 for the saltwater fish.
This dip should be no less than 3 minutes and no more than 5 minutes to be effective. This is very effective in removing oodinium and to a slightly lesser extent, Cryptocaryon directly from the fish (including gills).
A 30 minute bath is also a useful saltwater fish treatment for diseases such as Cryptocaryon. This is best used in conjunction with the other recommended treatments above as by itself is not likely to affect a full cure. I would make sure to adjust pH so that there is no pH shock.
Consider the use of Garlic preparations in fish food, such as SeaChem Garlic Guard as part of your Cryptocaryon prevention regimen, as while I have not found this to be a effective in most instances by itself, it MAY be another helpful preventative when taken with other methods, including optimum water conditions.
Here are a few myths about Marine Ich (Crytocaryon):
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