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Pond Maintence - Repairs - Upgrades
Pond Maintence - Repairs - Upgrades

Common Parasites and Treatments - Simi Koi Pond Maintenance

Pond Maintence - Repairs - Upgrades

Common Parasites and Recommended Treatments

By Karl Schoeler


At best, parasites open the doors for bacterial infection. At worst, they are carriers of it. That is why it is so important to try to identify them and treat for them properly.

While treating for parasites is very important, treating the resultant ulcerated area is equally important. Some will say to use hydrogen peroxide, then iodine, then dental adhesive to cover the wound. I have no argument with using all three, if they are available and you're proficient treating with all of them so the fish is not left on the table too long. Most are not. Iodine is extremely effective. Swab the wound thoroughly making sure to get underneath the skin and/or scaled edges. Remove any loose scales during this treatment as they will fall off anyway. This is generally a one time treatment. Further swabbing if any healing is evident will injure the new tissue which is slowly forming around the wound(pale pink to white in color). Further deterioration of the ulcered area after a thorough swabbing indicates the need for a more accurate parasite discovery or a more accurate dose of antibiotic or a change in the antibiotic used.


Be aware that there are companies and individuals who are marketing remedies which purport immediate healing just by dumping it into the pond. The labels will say it will cure just about anything and smell good doing it. Label claims such as this should make you wary; for good reason. These products generally don't work. Yet they are packaged and sold in nearly every garden store across this country. Go figure. If you find a product which will do just about everything, don't count on it.

KMno4 - Potassium Permanganate:
Potassium permanganate is capable of doing great things in terms of parasite control, but it is also capable of rapidly killing all your fish if used improperly. This is a poison. The "dip", which is described further on in the Sticky is very effective and is fairly safe because of it's precise nature. PP, when used in a pond setting is only as good as the person using it. Too strong and the fish will suffer and die. Too weak and the parasites will laugh at it.

For it to be effective in a pond the pond itself must be in fairly good shape, clean and free from organics(waste-plant debris etc.). The pond capacity(gallons) must be known. No guesswork on this.

For microscopic parasites excluding flukes use 2ppm KMNo4(potassium permanganate) in a clean pond. Two consecutive days and do not reverse the chemical. Add aeration. Be prepared to reverse the treatment with dechlorinator. Before you do this treatment for the first time it would be wise to discuss it on this forum. Start a thread.

The Dip
A dip of 8 grams KMN04 per 40 litres of mid-seventy degree water can be used but for no more than 2.5 minutes. Precise measurement is critical. Aerate. This dip requires several containers as well as an uncontaminated pond or q-tank to place the treated specimens. Pre-dip and post-dip containers are a must. Make sure they can be covered securely. This is a bit over 200ppm! Dips only work if the container(pond)the treated fish are being returned to is parasite free.

A gram scale is required to measure this chemical. Please calibrate it frequently.

For 1000 US gallons here is a brief chart:

PPM---------------Grams needed:


Any dechlorinator or hydrogen peroxide will reverse this chemical. Make sure you have enough to neutralize at least twice the amount used.

ProformC or Formaldehyde and Malachite Green:
This treatment is safe at temperatures of 55*F to 80*F.
FMG is effective on most microscopic parasites except flukes. This is a poison. It is dosed in amounts which will effectively kill the parasites without killing the host. Overdosing may damage or kill your fish. Formaldehyde is generally available from farm supply stores. It is 37% formaldehyde and 11~12% methanol. Commercial mixes such as ProformC are available from pond and koi suppliers. While it is a bit weaker it still works well. It also gives the end user a larger margin for error. It is 22% formaldehyde and about 7.5% methanol.

The following treatment is "off label": Two treatments, day one and day three. No water changes. Then a third dose combining ProformC and Praziquantel, AFTER a 50% water change. Another treatment should be considered after seven days AFTER a 50% water change. See the paragraph below for Fluke Specific treatment. A small percentage of salt in the water will not affect the treatment or the fish. This treatment is for all parasites and it is temperature/life cycle dependent. Flukes can take 30 days to eradicate if the water is in the low sixties. This takes several retreatments. Warmer waters reduces the time frame.

Malachite Green Stock Solution
28.4 grams makes one gallon. Thereafter use one drop per gallon.

Praziquantel: Gill and Skin Flukes:
A trematodicide. Praziquantel induces a rapid contraction of schistosomes(a worm or fluke)by a specific effect on the permeability of the cell membrane. The drug further causes vacuolization(causes more and larger spaces or cavities within each individual cell)and disintegration of the cells as well as the Schistosome tegument(the fluke body covering). Bursting of the cell walls might be a much simpler way of describing it and may be equally correct.
Praziquantel must be ingested by the fluke to work. The dosage is one gram per 100 gallons of water. Currently the directions suggest using level tablespoons to measure the product. That is a mistake. In my experience a level tablespoon may hold anywhere from 2.5 to 4.5 grams of product. Not only is this wasteful and inaccurate; it is also very expensive. Please use a gram scale. Calibrate it often.

Since it does not mix readily with water a label dosage ProformC may be used, or it can be dosed with the ProformC as part of the treatment described above. Once it is fully dissolved it does not seem to filter out or precipitate. It simply degrades over time. When using Praziquantel, the water temperature should be in the mid-seventies(US). The first and all succeeding treatments should last seven days each whether treating for gill flukes(Dactylogyrus) or skin flukes(Gyrodactylus). 25% water changes should be made between treatments. Redosing will immediately bring it to the strength needed to kill flukes. I strongly recommend a second if not a third application of this product due to the life cycle of the flukes as well as the thickness of the slime coat on Koi. In colder waters (60*F to 70*F) a third and even a fourth application should be considered when treating for gill flukes. Because of the cost of Praziquantel and the reduced treatment time it is well worth the effort to bring the temperature up to optimum.

Praziquantel as a kicker:
At times I've had situations where the standard doses and protocol of the ProformC and Praziquantel simply doesn't seem to work. In those situations I dose with a standard dose on day one. Then I wait 48 hours and redose with another standard treatment and allow that to stand for ten days. At the end of ten days I scrape and scope. If the water temperature is in the mid-seventies the flukes will be gone. Lower temperatures will require a repetition of the treatments after a 50% water change. I have never seen any ill effect whether in soft or hard water with this treatment. Although I am simply using ProformC as a mixing agent I like to see it used at full dosage just in case there are other parasites not foud in the scrape and scope procedure.

Know that this product has been accused of burning fins and suppressing the immune system. This accusation has been substantiated by several members of Koiphen. In the UK, there are more reports surfacing regarding the long range effect on the immune system as they have been using it for several years longer than here in the US. Therefore I would strongly urge that it be avoided. There are several methods for reducing flukes which are much safer. Not recommended here.

Organphosphates-Fluke Tabs:
Fluke Tabs work well in waters where the Kh is less than 170ppm. Above that the poison is bound by the water and becomes ineffective. Attempts at double and triple dosing in high Kh waters results in killing the flukes AND the fish. There are tests taking place currently to verify the accuracy of this information.

An older type dewormer which seems to work at times, the dosage is 1 gram per 100 gallons. and is used the same way as Praziquantel.
Chloramine T:
For bacterial gill disease. Dosing is 5.8 grams per 100 gallons, three to five times consecutively. This will no doubt kill your filter so either shut it down or bypass it. Do not mix this with any other treatments.

Dimilin(diflubenzuron 25% wettable powder):
Actually this is an insecticide for greenhouse use. This powder works well in eradicating anchor worm(Lernea)and fish lice(Argulus). One gram will treat 3000 gallons. It is quite forgiving and an overdose usually will not cause irrepairable harm. The parasites should be removed by soaking them in iodine or potassium permanganate paste and pulling them carefully with a tweezers. Sedating(described below)the fish will prevent uncontrolled thrashing and further damage to the fish during this process. No ill effect is noted from sedation.

There are liquid forms of Dimilin on the market. Follow the label directions.


Salt has been used on such a large scale and usually for no reason that most parasites are resistant to it. Therefore it is adviseable to use salt only when nothing else is available and then at at .6%-.7%. Notice the decimal point.

Exception 1:
Salt is known to protect fish from nitrites. The percentage of salt in this case is.15%. When adding fish to a pond or q-tank pay attention to ammonia and nitrites!

Exception 2:
Salt is required, at least so the story goes, when using Elbagin(a Japanese water column antbacterial agent very similar to Furazone Green). The percentage of salt in this case is .6%.

Exception 3:
Salt will aid in osmotic regulation of an immuno-depressed fish. New imports, as well as fish with bacterial infections are sometimes treated to aid their recovery. However this practice is no longer so widespread as it is recognized that overuse of any medicine leads to resistance and diminished effect. The percentage of salt used this way varies. Be aware that salt may adversely affect some medications.

Exception 4:
Two parasites can still be controlled successfully with salt. They are Chilodonella and Ich. The percentage of salt in this case is .6%. The treatment is not too temperature dependent and the duration of the treatment should be 14 days. Most other parasites are no longer deterred by salt.

Since salt occurs naturally in most waters, it is unnecessary to add it to pond water for ANY health reasons except those listed above and prevention of nitrite poisoning during the cycling of a filter. For informational purposes here is how to calculate salt:

.1% salt in 100 US gallons is .8333 pounds.
.1% salt in 1000 US gallons is 8.333 pounds.

.3% salt in 100 US gallons is 2.5 pounds.
.3% salt in 1000 US gallons is 25 pounds.

.6% salt in 100 US gallons is 5.0 pounds.
.6% salt in 1000 US gallons is 50 pounds.

.15% salt in one US ton(264 gallons) is 3.313 pounds.

Salt and Nitrites:ine Dosage is .15%. Salt will slow if not stop the uptake of nitrites. Yes, it is listed and described here twice.

Fungal Infections
Sap or Saprolegnia is the main genus of water molds which can bring about significant fungal infections in fish and eggs. It's safe to say that all ponds have water molds in them. Unless the fish are compromised the slime coat will, in most cases, protect the fish from an invasion. Sap invades epidermal tissues In common with all molds, it does so by secreting digestive enzymes into the surrounding areas. Since enzymes in general break things down it's easy to understand that this secretion enables the fungi to more easily absorb nutrients from the affected area. SAP slowly is digesting the fish! at this point it is called saprolegniasis.

SAP can spread over the entire body, but is usually spotted as pale white or grey patches. Sometimes it will be green if algae has been caught in it. It is usually considered to be a secondary infection seen after damage to the fish skin or gills. However it can be primary as it is temperature dependant, occuring in cooler waters as a consquence of immune system shutdown.

SAP Treatment
It is generally agreed that Malachite Green is by far the most effective treatment. Be careful with this stuff! Eye and skin protection is required. A stock solution can be made with it and it is applied topically to thoroughly and deeply clean the wound. A dental adhesive may be applied afterward if desired.

Stock solution: 28.4 grams makes one gallon. To treat directly use the stock solution straight. For other treatments use one drop per gallon.

Treatment is should be made as soon as possible along with determining the actual cause of the invasion and dealing with that as well.

Columnaris: Mouth Fungus; Fin Rot, Cottonmouth Disease:This is not a fungus or a mold. This is a bacterial infection-gram negative. The problem is that it can somewhat resemble SAP. Symptoms include grayish white spot on the head, gills or body sometimes surrounded by a reddish tinge. It can be topically treated with malachite green and then given antibiotic injections per the charts listed in that section.


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