Drugs are the surefire way to treat parasites however usually this requires removing fish ( all of them) from the aquarium. There are some alternatives discussed on this page however these are never 100% effective. New technologies are coming out which have not been proven but we are currently exploring. Contact us to use discuss combinations of biological controls and new drugs and therapeutics if you are interested in trying to control parasites such as Cryptocaryon in your reef and have questions after reading these pages.
Formalin: Formulated as 37% formaldehyde, formalin is a medication which is actually a poison and will kill any organism at high enough concentrations (it’s used to preserve biological specimens). It’s mechanism of action involves creating cross linkages between cell membrane proteins and disrupt normal function. Formalin is good for small protozoan parasites like oodinium (velvet), brooklynella, and cryptocaryon most of the time, however it works in some capacity against most microscopic and macroscopic disease causing organisms. The idea is that simple animals are less able to cope with nit’s toxic effects. It is usually effective against external platyhelminths: the flatworm planarians/ trematodes/digenean flukes but it doesn’t work on internal tapeworms: cestodes or digean flukes. It It wont treat internal parasites nor will it have any effect on bacteria (and actually may cause further stress and even burn like lesions on certain fish which may create opportunistic bacterial infections. The most common treatment dosage is 25 ppm (about 1 ml/10 gallons of tank water). This will kill any invertebrate in the tank and should be used in either fish only tanks (will also destroy live rock) or in quarantine tanks. This concentration also works for dips, which is a good trick for knocking off flat worms. Formalin is notorious for depletes oxygen from water. The oxygen decreases at a rate of 1 mg/liter per 5 ppm (regular water oxygen saturation is 8 mg/l) and so regular concentrations for therapeutic effects bring oxygen levels dangerously low ( around 3-4 mg/l)and supplementary aeration is necessary. A company named Aquarium pharmaceuticals sells a very cheap Formalin and a product called "quick cure" which is a formalin/ malachite green mixture at a concentration to be dosed at something like 1 drop per gallon daily (use as directed though). The amount of times you repeat treatment of dips or the length you treat and re-dose a bath is dependent on the life cycle of the parasite. In biological systems, formalin does not leave the water as gas in any appreciable level compared to it getting used up by reacting with organic compounds. I systems with high organic loads, formalin will actually only be in circulation for a few hours. In low organic load systems, such as small clean quarantine systems or five gallon buckets of clean reef tank water, it can stick around for days. Certain fish are more susceptible to formalin damage. Baby fish or fish stressed and prone to oxygen depletion such as shipped green chromis are generally not good candidates for formalin dips or longer term bath treatments. Here is a link to an in depth guide for formalin treatments, though it focuses more on freshwater species. aquaculture.http://edis.ifas.ufl.edu/pdffiles/vm/vm06100.pdf
Copper (copper sulfate/copper citrate/ cupramine): Copper is a metal ion which is also basically a poison to any organism at a high enough concentration. Copper treats most external protozoan and flatworm parasites. It is not very effective against crustacean parasites (parasitic isopods/copepods and the fish lice argulus/branchiurans) or marine leeches. Copper is generally run at .2 ppm and only the salifert test kit we have found for the hobby level can accurately tell you where the levels are at within a respectable range. (API, red sea, Seachem don't seem accurate enough or the colors are too close). Fish in general become lethargic and anorexic around .4-.6 ppm with copper sulfate and copper citrate and around .6-.8 for cupramine. Some fish, such as seahorses/mandarins/lionfish/dwarf angelfishes/any already stressed or sick fish, are hypersensitive to copper though we have pretty reliably treated those species with cupramine. A very important note: Do not use ammonia binding compounds (amquel/prime) when using cupramine (and it’s unclear about the other coppers but why risk it) but it turns the active copper 2+ ion to the more toxic copper 1+. This same mechanism happens when using a UV sterilizer with cupramine and so it is imperative to turn those off when treating. Reports and personal experience of copper overdoses include lethargy (fish acting dull, agitated, and unresponsive) anorexia (fish not eating), and even neurological signs like blindness. We have seen a temporarily blinded powder blue tang and a regal angelfish on separate occasions from copper overdose. Another important warning when using cupramine is that the dosing directions on the bottle are not clear about the therapeutic dose. They explain dosing in terms of what volume to add to get to .5 ppm, however this dose is not necessary and actually getting close to a dangerous level for some fish. Therapeutic levels to treat most protozoan parasites is .2 ppm (.18 actually) so copper levels including cupramine should ideally be kept around .25-.3 ppm.
Praziquantel: Is an anthelmintic drug (worm killer) which in land animals is generally used to treat tapeworms but in marine fish is most commonly used to kill external monogenean flatworms like neobenedenia. It is also commonly mixed into fish food in order to clear intestinal tapeworms usually from wild fish (see fish food formula for dosing instructions). The drug is absorbed in land animals through the intestines however is quickly degraded by the liver.The product prazipro is expensive but easy to dose as directed and we recommend using this for tanks less than a few hundred gallons. Anecdotally this drug is “reef safe” insofar as it does not hurt corals directly. Treating a reef should be done with caution as many susceptible animals, worms and flatworms, may live in the rock and sand and a spiraling water quality scenario may follow treatment. Watch water quality and be ready for a "mini cycle". If needing to treat a large tank or long term running a bunch of quarantines, looking into into praziquantel powder for economic reasons is reasonable and the places we recommend for buying drugs sell discounted “prazi” in larger quantities. Praziquantel powder is extremely hydrophobic (does not mix well in water) so using a mesh net or stockings to mix it into the water, or dissolving it into a small amount of alcohol (vodka) is usually necessary. When doing this, do not be surprised the next day if the water is a little bit cloudy from a bacteria bloom. Make sure in this case to maintain goot aeration in the aquarium.This drug may be removed from a system with activated carbon or by turning on your skimmer. If used often in a system, new evidence suggests that praziquantel actually may be broken down prematurely by bacteria. This drug does decrease the efficacy of Chloroquin and is not recommended to be used concurrently. There is anecdotal information about praziquantel being effective at removing GI nematodes when given as a food.
Chloroquine: Produced as chloroquine phosphate, this antimalarial has a long half life and we have been using it in quarantine for years to suppress cryptocaryon, amyloodinium, and probably other unidentified protozoan parasites. It is dosed at 10 ppm ( 10 mg / liter) with a redose once 5 days later. We move the fish out after 12 days or do a water change and re-dose proportionally. There is limited research on the use of this drug in aquaculture and aquarium fish however it is becoming more popular in public aquariums and ornamental aquaculture facilities. It has been used as an alternative when certain strains of cryptocaryon appear to develop a resistance to copper. The major problem with this drug is that it cannot be measured in the water without a spectrophotometer, which is very expensive. It is possible that in some systems, through an unknown mechanism, chloroquine is broken down to levels where disease causing protozoan organisms which it is supposed to treat, can survive and cause problems.This drug may be removed from a system with activated carbon.
Trichlorfon (dylox-80 is the most common easily dissolved form but a dozen trade names exist): An organophosphate (neurotoxin) that kills many of the metazoan (larger) parasites we see on fish. This drug kills flatworms, marine leeches, and copepod parasites as well as most of the protozoan parasites. It has a short half life and can be dosed a few times to break life cycles, but this is generally considered a harsh drug and many species are sensitive. We have used this to treat flatworm and copepod infestations many wild fish and elasmobranchs (sharks and rays). This drug is responsible for problems that the Georgia Aquarium has had with whale sharks (so all of you with whale sharks watch out).
Methylene blue: This is an antimalarial drug related to quinine (in tonic water) and chloroquine and has another effect which was used in humans; it mitigates cyanide poisoning by returning methemoglobin (oxygen not capable of binding) back to hemoglobin. This is valuable in aquarium for fish that have been exposed to high levels of nitrite (causes methemoglobinemia) as it returns the blood to a condition where it can carry oxygen. Increases in nitrite levels are common during the tanks “cycle” or when a fish is transported long term in a bag. Treatment with methylene blue is less valuable in salt water because the chloride ion competes with nitrite for absorption into the gill and usually marine fish don’t have problems with nitrite poisoning. The scientific literature hasn't demonstrated any real beneficial effect of using methylene blue in the few papers which have been published however only a few fish species (live bearers) under a few circumstances( dense fish bags similar to a shipping scenario) have been explored.It has been used by many experienced aquaculturists for a long time and we feel like there's something that it works to keep fish healthier in transport that scientists have not isolated to explore thoroughly. It may be a good idea to use this during acclimation if you have it on hand. Besides staining hands and clothing, there are no adverse effects if treated as directed and methylene blue may knock off a few straggling protozoans from a healthy fish or may help a fish better oxygenate blood in times of stress. This drug may be removed from a system with activated carbon.
Non-Drug Treatment Options (herbal and biological control)
The herbal and reef safe treatment options are not guaranteed and are often compared to snake oil. They are a variety of tea extracts and melaleuca/eucalyptus derivatives or clove oils which all have been shown to have some antibiotic / anti parasitic properties but have not been qualified or substantiated in any way for specific marine fish infected across a variety of environments. We have seen so many folks suckered into buying 100 dollars worth of rid-ich or no-ich and irritated their invertebrates, scummed up their skimmer, and done nothing for the disease.
What can work to mitigate disease is biological control. Neon gobies, if large enough, will eat flatworm parasites from fish. Juvenile hogfish, porkfish, and many baby angelfish (french/emperor/asfur) will clean cryptocaryon cysts off of other fish in some capacity (parasitised fish willing). Cleaner shrimp such as the skunk, blood, and even coral banded shrimp will clean external parasites from fish. Even little anthias or chromis have been known to browse each other and other fish for parasites. Cleaner wrasses will clean other fish rigorously however these fish generally don't do well in captivity as they often don't learn to eat anything else( see specifics in fish issues section).
Something else which may work and is essentially copying real coral reefs is environmental control. In a well established reef, it is common for cryptocaryon to stay ambient at subclinical levels similar to how it works in nature. We believe that things like hermit crabs , sifting gobies, and sea cucumbers are eating the parasites when they are in the stage that grows in the substrate(tomonts), and corals and skimming pull out the infective swimming stages(tomites, theronts). It may be possible to load up on blue legged hermit crabs to try to reduce the parasite burden as a first shot in the dark if you have an established reef. It might be the equivalent of siphoning the bottom of a bare bottom quarantine to pull out tomonts (might physically remove 90%? of the parasites)