Oodinium (oodinosis, oodiniumosis) of aquarium fish. Symptoms and treatment. Photo.

The single-celled organism Piscnoodinium pillulare (synonym Oodinium limneticum), a dinoflagellate, is the causative agent of oodinium, oodinosis, velvet disease, coliza disease, and pillulariosis. The fact that the illness has so many catchy names (there’s also "gold dust") is obviously not accidental. At the moment, oodinium is the most widely used scientific term for this illness. After coming into contact with oodinium, aquarium owners develop a strong dislike for the material and develop a habit of closely examining their fish to see if they have the small, grayish or golden "sand" that is the only obvious sign of oodiniasis.

MORE ABOUT THE SYMPTOMS OF OODINIASIS

What is shown in the collage-splash for this article? Before us is a lalius (Trichogaster lalius, earlier this genus was called Colisa) sick with oodiniasis (oodiniasis). Fish from the genus Colisa are especially susceptible to oodiniasis. Hence one of the names of this fish disease – colisa disease. The symptoms of the disease are as follows: the skin on the fish"s head is destroyed in places, the body, fins and gill covers are covered with very fine golden-yellowish dust, which is very, very difficult to see with the naked eye. But through an ordinary magnifying glass, numerous small light dots-tubercles are already clearly visible. Click on the splash picture for this article: a high-resolution photo will open. Approximately the same can be seen with examining fish infected with oodinium with a strong magnifying glass.
You can only examine these tubercles in detail, which represent the vegetative stage of the parasite"s development – oodinium trophonts, under a microscope. The picture-splash to this article (round insert) shows how oodiniums look under low magnification of a microscope. But in all their glory, oodiniums appear before us only under high magnification. These are pear-shaped, oval or round bodies with granular filling and a light-colored "eye" – nucleus. They have a golden or yellowish color, as they contain numerous chloroplasts. The oodinium trophonts are completely immobile, unlike the ichthyophthirius trophonts, and in their appearance they are very different from each other. Therefore, microscopy allows us to confidently distinguish oodinium from ichthyophthirius, whereas when examining a sick fish with the naked eye, amateur aquarists often confuse oodinium with the tropical form of ichthyophthirius.

BIOLOGY AND SYSTEMATIC POSITION OF THE PATHOGEN OODINIOSIS.

The agents that cause oodiniums are classified as Phytomastigophorea in the order Dinoflagellida. These organisms share characteristics with both plants and protozoa, such as having chloroplasts and the ability to photosynthesise. Particular consideration should be given to this final situation. In the absence of light, oodinium viability is significantly decreased as photosynthesis is not possible. When treating fish, this aspect of oodinium biology can and ought to be applied. Fighting oodinium is made simpler by shading the aquarium.

Fig. 1. Life cycle of the oodinium pathogen. From the book: Grishchenko L.I., Akbaev M.Sh., Vasilkov G.V. "Fish diseases and the basics of fish farming", Moscow"Kolos", 1999.

The figure above shows a schematic representation of the life cycle of the oodinium pathogen. Oodiniums attach to the fish body and parasitize in the trophont stage (a). At a water temperature of 25°C, the growth period of trophonts lasts about 6 days. Then they leave the host fish, fall to the bottom or plants and become tomonts (b, c). Tomont divides repeatedly, forming up to 256 tomites, which are transformed into small mobile dinospores (gymnospores) (d, g). Dinospores swim with the help of flagella and search for a host fish. The entire division process at 25°C takes 6 hours in the light and 8 hours in the dark. At 15°C, division continues for 20-22 hours in the light and 30 hours in the dark. Dinospores at 25°C can survive on their own for only 24 hours. They die if they do not attach to a fish during this time. Thus, the life cycle of oodiniums in a warm-water aquarium does not exceed eight, maximum nine days. However, at a water temperature below 15°C it increases significantly. ( Information from the book: ed. N.A. Golovina and O.N. Bauer"Ichthyopathology", Moscow"Mir", 2003.)

Fig 2 . Scheme of the structure of the oodinium trophont. Based on materials from the site

We note once again that it is important for an aquarist to be able to distinguish oodinium from ichthyophthirius, since the methods of treatment of these diseases are different. What helps against ichthyophthirius is almost useless in treating fish from oodinium. Without experience, you can confuse advanced oodinium (oodinosis) with the tropical form of ichthyophthirius, and an incorrectly chosen treatment regimen will lead to the loss of precious time and the death of sick fish. Since it is better to see once than to read a description a hundred times, I have provided photographs of fish sick with oodinium. Usually oodiniums are almost invisible to the naked eye, while the dermoid tubercles under which ichthyophthirius are hidden are quite visible. Compare these photographs with those posted in the article about ichthyophthirius and feel the difference.

Picture 1: A juvenile Betta splendens Siamese fighting fish suffering from oodinium (oodinosis). The same fish is seen in the picture at various magnifications. It is only slightly enlarged in the inset at the bottom of the picture, so its dimensions are almost natural. The oodiniums on the fins, however, are only clearly visible when the fish are magnified multiple times (upper fish). To view the larger image, click on it.

Picture 2: This collage was put together using a similar idea.The only way to see "gold dust" clearly is with a magnifying glass. There’s a female Notobranchius Guenterii in front of you. Teethed carps that lay eggs are susceptible to oodinosis, particularly in soft water.

Photo 3: It’s quite hard to detect oodinosis in Indian glass catfish (Kryptopterus bicirrhis). A substantially enlarged portion of this image can be found below (marked with a frame). The oodiniums on the back of the catfish are plainly visible there.

Photo 4: Oodiniums under high magnification from a microscope (inset at top right) and on the body of a glass catfish (about twenty times magnification).

Oodinium is an insidious disease. It can barely flicker in an aquarium for years, and an aquarist will not even suspect about it. Adult fish very rarely die from oodinosis, and often do not even show any symptoms of this disease. If the conditions are good, the fish are only carriers of the infection and do not get sick in an obvious form. Only sometimes, for some unknown reason, they scratch themselves against stones and plants, and also suddenly turn pale and cringe, twitch sharply. Sumatran barbs periodically and for no apparent reason for a second or two, trembling their fins, hang head down as if fainting. However, if the conditions worsen, for example, with excessive supply of carbon dioxide to the aquarium or with a jump in nitrites, the disease can worsen and lead to the death of some fish. In a well-maintained aquarium, nothing terrible happens.
And only when the aquarist manages to get fry, he understands that something is wrong. The fry eat well, but grow poorly. After some time, the fish begin to die – not all at once, but several pieces a day. More in after a week or two the fish begin to look "squeezed", swim stiffly and gather in the corners of the aquarium or at the surface of the water. The fins stick together and soon begin to split. Only broken rays remain without interradial tissue. The skin peels off the fish in patches in places. Plague begins. The entire surface of the body of sick fish is covered with numerous clusters of parasites. They look like gray or yellowish "sand", and now, especially with properly installed lighting, they are visible quite well, since they form whole clusters. Some aquarists see here a certain analogy with velvet. Hence one of the names of oodiniasis (oodiniasis) – velvet, or velvet disease. Sick fish retain their appetite almost until death, so if this "velvet" is not noticed, then oodiniasis can be missed and treatment cannot be started on time. Waste of time will inevitably lead to the death of the fish.

Image 5. Oodinium clusters captured on the tail fin of a Siamese fighting fish using a microscope (8*7 + camera magnification); the photo is displayed above. This indicates that the fish’s oodinosis infection is not too severe. But trophont clusters are already present. If you look at the fish without magnification, those are the ones that are visible on the betta’s tail.

Picture 6. The interradial tissue of the fins and gills will be rapidly destroyed by the oodiniums if you do not combat oodinosis (oodinosis) (40*4 + camera magnification). The interradial tissue is totally destroyed at the location of the arrow, which indicates a deep split in the caudal fin.

Photo 7. A fragment of the gill arch (large arrow) of a sick Siamese betta under a microscope (8*7 + camera magnification), in the insert there is a greatly enlarged oodinium trophont attached to the gill petal. The same trophont is also visible in the main photo under the lower right corner of the inset. Oodinosis leads to the destruction of the gill petals. At the same time, both the cartilaginous base of the gill petals (one of these cartilaginous strands is marked with a green arrow) and the respiratory folds (the white arrow marks one of them) are destroyed. It is evident that the cartilage of many gill petals is destroyed starting from the tip of the petal, the respiratory folds are edematous, filled with stagnant blood. Probably, the toxins secreted by oodiniums cause degradation of the gill petals (You can read about how the fish gills are structured and function here ). Thus, with oodinia, the respiratory function of the gills is significantly impaired. Consequently, fish sick with oodinia can die from suffocation, especially if you thoughtlessly use a common universal recipe and raise the water temperature to 30-32 ° C. You should not do this without assessing the degree of damage to the gills.

Photo 8. 1 – Siamese fighting fish, sick with oodiniasis (oodiniasis) for a long time. The disease is largely suppressed, but not completely. The clusters of oodinium on the body of the fish are no longer visible, but the cockerel is left with severely damaged skin: significant erosions (arrows) are visible on the head (4) and back, formed at the site of parasite clusters. Why they occur becomes clear if you look at how the oodinium trophont attaches to the fish"s skin – 2. Here is a photograph taken under high magnification of a microscope of an immature trophont found on a scraping from the body of this cockerel. The arrow points to the so-called "rhizoids" – root-like processes that not only hold the trophont on the surface of the fish"s body, but also destroy skin cells. The trophont feeds on "juices", and may also be fragments of dying tissue. Unfortunately, "rhizoids" are very poorly visible unless the preparation is specially stained. An aquarist faced with erosion of the skin of fish with chronic oodinosis must take measures against the occurrence of secondary infections in the affected areas. Such preparations as Stress Coat, Splendid Betta Complete Water Conditioner, and especially All-Natural Melafix or Pimafix will greatly help him with this. 3 – a reproduction cyst found on a scraping from the body of this cockerel.

WHICH AQUARIUM FISH ARE SICK WITH OODINIOSIS?

What else is important to know about oodinium (oodinosis)? Oodiniums can parasitize on all types of freshwater fish. But, as a rule, only labyrinth fish, carp (barbs, danios, rasboras) and egg-laying toothed carp fish get seriously ill. Juniors and fry are especially susceptible to this disease. Oodinium can be brought into an aquarium along with completely healthy-looking cichlid fish, which usually do not suffer from oodinosis in an acute form. Perhaps, small populations of oodiniums can exist for a long time in the mouth and gill cavity of fish without causing dangerous outbreaks of numbers. There is every reason to believe that not all mature tomonts immediately begin to divide and soon produce dinospores. Probably, some of them form a resting cyst, which may not develop for months and is very resistant to aquarium treatments with medicinal products.
There are also predominantly gill forms of oodinium, when on the body of a sick fish oodiniums are either completely absent, or there are very few of them. But the gills can be very badly affected, which can cause the death of the fish.

Photo 9: Leporinus fasciatus dies from oodinium (oodinosis), the gill form. The gills display a large number of trophonts.

MYSTERIES OF OODINIOSIS.

Is oodinium (oodinosis) well studied? No!
There is a lot of conflicting information in the literature about the number of species of the pathogen of this disease, about how oodiniums attach to fish (under the epidermis or not), about how the reproductive cyst is structured: does it have a protective shell or not, where exactly – on the fish or on the substrate does multiple division of the tomite occur. In the simple diagram of the life cycle of oodiniums, given at the beginning of the article, the sexual process is not shown at all, but it is probably there. Descriptions of the sexual process in Piscnoodinium pillulare I am in an accessible I couldn"t find it in the literature. But it may be associated with the formation of dormant cysts. In addition, the life cycle of oodiniums can change in the same way as that of tropical ichthyophthirius. I observed the division of tomonts and the hatching of dinospores on a temporary wet preparation of a scraping taken directly from the body of a sick fish. A reproductive cyst found on the body of a Siamese fighting fish is shown in photo 8 (3).

Picture 10: A scraping of a red parrot imported from Malaysia that contains oominiums. Compared to the typical Piscnoodinium pillulare, they are noticeably oblong in shape, suggesting that they are a distinct species. This is where the trophont division (the leftmost one) is visible; it happens right on a fish that has an oodinium infection. I’ll wrap up by providing an example of an extremely uncommon oodinium. Trophonts are found close to the anus in the fish’s body cavity.

Picture 11. Oodinium-sick Eutropius buffei (Pareutropius buffei), also known as striped glass catfish. There’s a cluster of oodiniums inside the translucent, thinning abdominal wall. To view the larger image, click on it.

Picture 12. Eutropiella buffei (Pareutropius buffei) abdominal cavity oodinium accumulation

TREATMENT OF FISH FROM OODINIOSIS (OODINIOSIS)

There are many methods of treating oodinium in literature and on the Internet, unfortunately most of them are not really effective. A truly effective and safe for fish (Not for plants! Remember, oodiniums are partly plants!) treatment in a common aquarium is with the antibiotic bicillin-5 (you can use bicillin-3, but its effectiveness is lower and the treatment lasts longer). Before treatment, it is necessary to determine the pH of the water . The antibiotic works much worse in an acidic environment. Optimal pH values ​​for treating fish from oodinosis with bicillin: 6.7 – 7.8. The water temperature should not be below 24°C. Optimum – 26-27°C. The aquarium should be shaded. Complete darkness is not necessary, but twilight is desirable, otherwise bicillin-5 will quickly lose its activity, and oodiniums will receive an additional resource viability due to photosynthetic activity. It is necessary to provide strong and effective aeration of the water. It is better not to feed the fish before treatment. Dosage: 750,000 – 1,000,000 or even 1,500,000 (the entire contents of the bottle) per 100 liters of water. In case of severe damage, it makes sense to take a risk and give the maximum dose of the drug, that is, one and a half million units of bicillin-5, but this dose should be given to exactly 100 liters of water, and not to a hundred-liter aquarium, in which usually at least 10-15% of the volume is occupied by soil and decorations, and it is usually not filled to the brim. After 14-18 hours, the fish in most cases are freed from oodiniums. The widespread opinion that it is almost impossible to influence trophonts attached to the body of the fish, since they are hidden under the epithelium of the fish, is incorrect. Trophonts, as can be clearly seen in the photographs provided in this article, are attached to the skin of the fish, penetrate inside only "rhizoids". Thus, the parasites are in direct contact with the aquarium water and with the drugs dissolved in this water. Bicillin-5 kills them very well. If the next day the "gold dust" is still visible on the fish, then change at least 30% of the water in the aquarium and add another full dose of the medicine. I have not yet met a variety of oodiniums that can survive repeated treatment with bicillin-5. After two days, add bicillin-5 again. Usually this is quite enough to eliminate oodinosis in the aquarium. However, it is still impossible to give a 100% guarantee that there are no viable cysts of reproduction in a dormant state in the aquarium. The awakening of these cysts is facilitated by the brightest and longest lighting, installing an oxidizer in the aquarium or adding hydrogen peroxide (3% solution from a pharmacy) directly to the aquarium at a rate of 20-25 ml per 100 liters twice at intervals of a day, increasing the water temperature by 2 degrees. These measures must be carried out for 4 days and then the aquarium must be treated with bicillin again.
You can treat fish for oodinium (oodinosis) in a separator. It makes sense to do this if there are valuable plants in the aquarium and it is important to keep them intact. Using bicillin-5 can slow down their growth and lead to deformation of new leaves. It should be noted that the use of bicillin-5 does not always necessarily lead to the suppression of plants. Two applications at a dosage of 750,000 units / 100 l usually do not entail dire consequences. When treating fish in a separator, as a rule, two treatments with bicillin-5 are enough. But the fish should not be returned to the main aquarium earlier than 8-10 days. At this time, the water temperature in the main aquarium should be 27-28 ° C. One third of the water volume should be replaced immediately after planting the fish. The first 4 days, the aquarium can be lit brighter than usual, and then shaded. Water changes, high temperatures and bright light will provoke the development of all dormant cysts. The dinospores released from them will not find host fish and will die. In the dark, they die faster, since they cannot feed on photosynthesis.
When treating fish and keeping them in the breeding tank, it is advisable to using special tests daily monitor such water parameters as pH, ammonia and nitrite concentration . 8-10 days is a significant period during which unfavorable conditions for fish life can develop in a small container with an unsettled biological balance. You should always be prepared for an emergency water change . In addition, it is very useful to have on hand a product that neutralizes the toxic effect of ammonia, for example, ammolok (API AMMO-LOCK) or NILPA antiammoniac. In the footer of this page you will find useful links that will help you buy everything you need to treat fish for oodinium.

How to treat fish for oodiniasis (oodinosis) if there is no bicillin-5?

Freshwater oodiniums are sensitive to the presence of table salt in the water. Fish with a low degree of damage can be bathed in a 1.5-2% solution, this procedure must be repeated 3-4 times. But not more than once a day. In case of severe oodinium, when bathing, first use only a 1% concentration of table salt. Adding tea to the aquarium will facilitate the regeneration of damaged skin of fish. For labyrinth fish (gourami, cockerels, laliuses, labioses), catfish corydoras and barbs, I would not recommend exceeding a concentration of 1.5%.
Oodiniums do not tolerate salts of heavy metals, especially copper. If the aquarium has fairly hard water: GH not less than 8° (3 or more meq/l), KH not less than 6° (2 or more meq/l), then you can use special branded drugs (see. list at the bottom of the page) for treating fish, which include copper, or simply a solution of copper sulfate. New drug NILPA Helamed allows you to treat fish in soft water – from 2 ° KH . It should be taken into account that all mollusks and crustaceans living in a given aquarium will die when treating fish for oodinium with copper! If their biomass is large, then significant problems will arise associated with a sharp deterioration in water quality during the decomposition of dead animals. This circumstance must be taken into account if sand Malayan snails melania live in the aquarium, the biomass of which is usually quite significant. Treatment with copper ions cannot be carried out if there are a lot of snails in the aquarium. In this case, you will have to catch the fish and treat them in a quarantine aquarium.
The concentration of copper ions that is effective in treating fish for oodinium (oodinium), that is, destructive for oodiniums, but relatively safe for fish, is 0.12-0.18 mg / l. Many literary sources suggest using significantly higher concentrations. Data on safe concentrations of copper ions in water are contradictory and this is not without reason. Copper toxicity is associated with the presence of organic acids in water, with hardness and with the natural background of these ions in the water constantly used in the aquarium * . It is very difficult to correctly assess all these factors in advance. Therefore, treatment should be started with the low concentrations indicated above.
To combat oodinium with copper, first prepare a mother liquor at the rate of: 4 g CuSO₄*5H₂O (this is copper sulfate) and 0.5 g citric acid per 1000 ml of distilled or boiled (boil for at least 20 minutes., let it cool and carefully drain the top layer, which is used) water. First, dissolve the citric acid, and then copper sulfate. The mother liquor contains about 1 mg Cu 2+ in 1 ml of water and, therefore, it is simple and convenient to use. For example, if you decide to use a therapeutic concentration of copper ions equal to 0.15 mg/l, and the water in the aquarium is 80 l, then you will need a total of 0.15 * 80 = 12 mg Cu 2+ . Therefore, 12 ml should be taken from the mother solution and added to the aquarium in small portions near the filter outlet pipe. The treatment period should not exceed 10 days. During this time, it is necessary to maintain the therapeutic concentration of copper ions. A day after the first addition, it is advisable to determine the copper ion content in the water using a copper test and add the required amount of mother solution to replenish the losses. Repeat these operations another day later. If it is not possible to determine the copper ion content in the water, then after the first addition, on the third and fifth days, add half the dosage of the originally calculated one.
Copper ions disrupt the metabolism of fish, slow down tissue regeneration and, if overdosed, can lead to the death of fish. As a specially conducted study has shown, if during treatment you use food soaked in a veto "starter" , then the harmful effects of copper ions on the body of fish and on nitrifying bacteria in the filter will be significantly reduced.

Treatment of aquarium fish from oodinium using the drug NILPA HELAMED.

Turn off the UV sterilizer and take out the activated carbon and oxidizer from the filter before adding the medication to the aquarium water. Don’t add hydrogen peroxide to the aquarium while it’s being treated. Ratio 7 ml/10 l, duration of exposure 5 days. After adjusting the water volume by one-third on the sixth day, repeat the process twice, a day apart. It is not advised to brightly illuminate the aquarium while it is being treated.

Additionally, medications containing quinine derivatives are used to treat fish from oodinium. Literature reports that medications like quinine sulfate and quinine HCl—the latter of which is less toxic—are available in the United States. Dosage: Take a long bath (up to three days) with 1 g per 100 l of water. Delagate and analgin-quinine are presently sold in pharmacies in Russia. Using these drugs for experimentation makes sense.

Oodinium can probably be treated in other ways. Furthermore, tried-and-true recipes might not always work. We can talk about all of this in the "Oodinium (oodinium) of freshwater fish – diagnostics and treatment" special topic on the Aquarium forum. An additional illustration of an oodinium practical diagnostic.

And for "snack," consider the increasingly well-known rasbora "Galaxy" (Danio margaritatus), which serves as an illustration of how challenging it is to detect oodinium on a small fish. Currently, oodinium illnesses in these fish are very common, but the owners are blind to the problem.

References:
1. "The Aquarist"s Encyclopaedia" (ed. by Gunther Sterba), Leipzig, 1983.
2. Dieter Untergasser. "Handbook of FISH DISEASES", – t.f.h, 1989.
3. "Regulatory data on maximum permissible levels of pollution of environmental objects with harmful substances", St. Petersburg, 1994.
4. Grishchenko L.I., Akbaev M.Sh., Vasilkov G.V. "Fish diseases and basics of fish farming", Moscow"Kolos", 1999.
5. Voronin V.N. Medicines in foreign ichthyopathy (USA). In the collection"Fish industry: series DISEASES OF HYDROBIONTS IN AQUACULTURE", issue.2, Moscow 2001, pp. 35-41.
6. Golovina N.A., Bauer O.N. "Ichthyopathology", Moscow"Mir", 2003.

Aquarium fish frequently contract oodinium, also referred to as oodinosis or velvet disease, a parasitic infection that causes symptoms such as a yellow or gold dust-like coating on their bodies, rapid breathing, lethargy, and appetite loss. To prevent recurrence, treatment for this disease includes putting the affected fish in isolation, raising the water’s temperature, administering certain drugs, and enhancing the water’s quality.

* It"s incredible, but true: the maximum permissible concentration (MPC) of copper ions in tap water is 1.0 mg /l. !? (GOST 2874-82) And we are discussing the fact that already 0.2 mg /l can be dangerous for fish. For comparison: the fish breeding standard is 0.001 mg /l. But the truth is with a very important caveat: "to the natural natural background". See. also the note to the article on biotesting. We must not forget that heavy metals seriously impair the ability of fish to restore damaged tissues; fish that have recovered from oodinium will have to restore their skin. The use of Vetom 1 will speed up the recovery of fish and minimize the harm of copper ions.1.
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