Preventative Medicine:
The best course of treatment is prevention. All new fish should be quarantined for at least three weeks. This helps ensure that the fish are healthy, but it also gives them time to get over any shipping trauma, to get used to a new diet, and to put on weight after withstanding often insubstantial feedings at retailers, wholesalers, and collecting stations. Best of all, this will occur in a competition-free environment.
It is my strong preference and my general recommendation to never add any medications to a display tank. In my experience, it is always better to remove all the affected fish to a separate quarantine/hospital tank for treatment. This ensures that none of the display tank's other inhabitants such as corals, bacteria, worms, amphipods, copepods, or mysid shrimp are affected. Also, if you keep the fish in quarantine for one month without infection, you can be sure that any Ich parasites and their eggs have hatched and died without a host. Note that Cryptocaryon irritans requires a fish host. They cannot complete their life cycle with the rock, sand, or any invertebrates.
Treatment Option 1 - Copper:
Copper is a highly effective medication against Cryptocaryon irritans when dosed and maintained in the proper concentration. I am going to abbreviate my advice and simply suggest to: "Always follow the directions of the manufacturer of whichever brand of copper medication you employ, and always use a test kit to verify the dosages." Copper has a narrow range of effectiveness and levels must be monitored at least daily.
Copper has several disadvantages in treating Ich. First, at too low a dosage, it is ineffective. Secondly, at too high a dosage, it could kill all your fish. Daily, or better yet twice daily, testing is required to maintain an appropriate and consistent level of copper. Even when within the appropriate ranges, some fish cannot tolerate copper. Some of the fish more sensitive to copper are lionfish, pufferfish, mandarins, blennies, and any other scaleless fish. Copper is also a known immunosuppressive, making fish more susceptible to secondary infections.
Invertebrates are extremely sensitive to copper and cannot be housed in a tank undergoing this treatment. Lastly, copper cannot be used in the presence of any calcareous media. Live rock, sand, crushed coral, and dead coral skeletons will all adsorb copper, rendering it useless a treatment.
Copper specifically targets the infectious, free-swimming theront stage of this disease, as being buried deep in the skin of the host protects the trophonts; the cyst walls of the tomonts are similarly impervious. Knowing this and the life cycle of Cryptocaryon irritans, monitoring and dosing as needed in the evening right before the lights go out is going to be the most effective method. This should ensure optimal treatment concentrations at the most beneficial time.
Copper is probably the most popular method of treating Cryptocaryon irritans, but is not my first choice. It is far too labor intensive for me to recommend to the general public, has a large risk of overdose, lowers the fish's resistance to other diseases, and can cause serious damage to the kidney, liver, and beneficial intestinal flora of the fish being treated. Damage to intestinal flora is what many hobbyists point to as a possible contributing cause for Head and Lateral Line Erosion (
HLLE), although there is currently no definitive cause of
HLLE.
Treatment Option 2 - Formalin:
Formalin can be administered one of two ways; either in short dips with saltwater or used continually in a hospital tank. The dosage for the continuous use is 1 ml of the 37% stock solution for every 25 gallons of quarantine tank water. I prefer the formalin dip to continuous use because formalin is a fairly toxic compound. Also, with no commercially available test kits to monitor the concentration, it would be difficult to dose an entire tank and account for evaporation, absorption, etc.
To prepare the dip, I take 5 gallons of tank water and add to it 3.75 ml of 37% formalin. I also aerate the water vigorously to ensure there is maximum dissolved oxygen. The dip should last 30 to 60 minutes. As when using any medication, it is best to monitor the fish's reaction and be prepared to act if it appears in distress. When the dip is complete, net the fish, place it back into the hospital tank, and discard the dip water. This protocol should be repeated every other day for two weeks.
I would like to remind readers of a few precautions regarding the use of formalin. First, it is a carcinogen. Formalin is an aqueous solution of carcinogenic formaldehyde gas, so gloves should be worn and the area should be well ventilated when using it. Secondly, formalin should not be used if fish have open sores, wounds, or lesions. It is likely to cause tissue damage to these open wounds. And lastly, formalin can rob the water of dissolved oxygen. That is why proper aeration is so crucial. For that reason, do not use formalin if the water temperature is 82*F or higher.
Treatment Option 3 - Copper & Formalin:
It is possible and sometimes preferable, like in the case of heavy infestations to use copper in conjunction with Formalin in a quarantine/hospital tank. The same warnings about sensitive fish still apply. If a fish is sensitive to either copper or Formalin, they are not safely exposed to the combined protocol. At this point, it is "cure or kill." You will either cure your fish or kill it from poisoning. It is the most aggressive and dangerous treatment described in this article.
Treatment Option 4 - Hyposalinity:
Low salinity has been demonstrated to be an effective treatment against Cryptocaryon irritans. A salt level of 16
ppt or approximately 1.009-1.010 specific gravity at 78-80*F for 14 days was reported to kill the parasite. I have never experienced problems when placing fish into a hyposalinity treatment, but have routinely witnessed fish showing obvious signs of distress when brought back to normal salinity levels too quickly. For that reason, I try to limit the specific gravity increase 0.001-0.002 points per day.
One of the alleged benefits of this treatment is the resulting conservation of energy for the affected fish. Reef fish have to constantly drink saltwater and excrete the salt to maintain the proper osmotic balance. Lowering the salinity of the surrounding environment eases this energy demand on the sick fish, thereby allowing them to expend more energy towards fighting the infection. On the contrary, keeping fish in low salinity means that they don't "flush" their kidneys sufficiently. After long-term exposure, this can cause kidney failure and kill the fish.
The drawbacks to this treatment are the same as for many of the treatment options discussed above. Invertebrates and certain fish will not be able to tolerate it, so you should not apply a hyposalinity treatment in a display tank. Sharks and rays are two fish groups that do not tolerate this procedure. I would also not recommend this approach in the presence of live rock or live sand. The hyposalinity treatment will likely kill the worms, crustaceans, mollusks, and other life in and on the substrate, causing a severe drop in overall water quality.
I have another word of caution when using this treatment. I would strongly suggest the use of a refractometer or perhaps a salinity monitor. Swing arm style box hydrometers are notoriously inaccurate. The glass, floating style hydrometers are better, but easily broken. An accurate measure of the salinity could mean the difference between being inside the effective treatment range or being too high and ineffective or too low and jeopardizing your fish.
Even given its few drawbacks, hyposalinity is a great method of curing infected fish of ich in a proper hospital tank. Of the treatment options discussed this far, in my opinion, it is by far the safest. While none of these options is appropriate for use in a display tank, and all have their drawbacks, weighing the pros and cons of each leads me to recommend hyposalinity above the others.
Treatment Option 5 - Daily Water Changes:
John Walsh related this method in a presentation given to the Pittsburgh Marine Aquarium Society, Inc. It is safe and effective for all marine fish and is my preferred first course of action. Fish are put into a quarantine/hospital tank and then everyday for two weeks the tank is completely cleaned and a 50% water change is performed. While the size of this water change may concern some aquarists who are not accustomed to water changes of this magnitude, as long as you are careful about matching the temperature and salinity, you should not experience any problems. This method helps to remove the tomites, tomonts, and theronts from the tank and lessens the chance of reinfection. The fish should remain in quarantine for an additional month to ensure the treatment has worked and to allow them time to gain strength.
This method is best used as a preventative when a fish is first acquired. It is also useful for mild infestations or when other more aggressive treatments cannot be used due to species sensitivity. The best thing about this kind of treatment is it is safe for all fishes and invertebrates. One of the other benefits is the daily water changes should help you maintain optimum water quality and therefore should stimulate the fish's immune system to combat any secondary bacterial infections that might be attacking the vulnerable areas where the Cryptocaryon irritans parasites have burrowed into the skin. This is in contrast to copper or Formalin, which are both immunosuppressive, and may actually promote secondary infection.
