Diseases of aquarium fish 3

Pond farming the most insidious. Therefore also the most feared disease of carp fishes. The disease characteristics common there, like roundish, flat, wall-like limited skin ulcers or strong spinal curvatures, are quite rare in the aquarium practice. On the other hand, the exceptionally strong distension of the abdomen, which is not so common in pond farming, often occurs in aquarium fishes. Last but not least it should be emphasized that in warm water aquariums almost never mass infections occur, but always only single, mostly older animals fall ill with infectious dropsy.

The pathogen, a bacterium (Pseudomonas punctata f. ascitae), occurs everywhere in the water. The possibility of infection in aquarium fish arises again in each individual animal, d.h., the bacteria that leave a diseased fish are not able to colonize healthy aquarium fish.

Endangered are only aquarium fish pre-damaged by other causes. Above all, abdominal dropsy can occur as a secondary infection in the case of gastrointestinal inflammation, visceral fatty degeneration and fish tuberculosis. This also explains why mostly older animals are affected, rarely young ones. Older fish often have gastrointestinal inflammation and fatty liver, but not young, still fast growing animals.

Disease characteristics of infectious dropsy

Infectious dropsy usually manifests itself in aquarium fish as increasing distension of the abdomen, dropsy, severe scaling and formation of blister-like water cushions at the fin roots. Rarely, goggle-eyes, very rarely, areal, wall-like, limited, coarse ulcers in the skin can be observed. The strong distension of the body leads to rocking swimming movements. finally to almost complete immobility. The cause of distension is the deterioration of one or more internal organs due to infection. As a result, fluid is secreted into the abdominal cavity and the abdomen inflates.

Treatment of infectious dropsy

Unfortunately, the infectious dropsy Treat successfully only in the initial stages. There are different agents on the market, which can be used to treat infectious dropsy.

Good husbandry and varied feeding are the best methods of disease prevention.

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Diseases of aquarium fish 3

The Hole disease mostly occurs in South American cichlids living in very soft water (z.B. discus). In American cichlids, which live in relatively hard water and therefore do not suffer from mineral deficiency, pitting disease occurs rather rarely. Hexamita symphysodoni, a flagellate with 8 flagella, is considered the causative agent. They seem to multiply very strongly especially in case of nutritional disturbances. But also stress, wrong water values or a high water load can be causes of the hole disease. In the course of such mass development, the pathogens enter through the blood into almost all organs of the body cavity and also into the skin.

Disease characteristics of the hole disease

Vascular blockages occur, especially in the area of the head, the eyes, the back and the lateral lines, which in turn cause small foci of decay in the skin. These are rejected, causing small but very characteristic holes, hence the name hole disease. These holes can heal or expand into crater-like skin defects. Secondary infections with other pathogens often occur at these sites.

Heavily infested fish become darker and darker, refuse to eat and are eventually very apathetic. Occasionally they recover temporarily, but then show a more conspicuous clinical picture.

Detection of the hole disease

The pathogens can be detected microscopically in the intestinal contents or fresh feces. In smears of diseased skin areas one usually finds only a few pathogens. The infection from animal to animal occurs via the feces, d.h., Pathogens excreted from one animal in the feces can easily enter the gastrointestinal tract of another animal.

Control of the hole disease

Many cases of Hole disease can be cured by optimal husbandry. This includes compliance with water hardness (for discus below 4°dGH). Further one should pay attention to a tidy basin mechanism. A naked discus tank, which is equipped only with a spawning cone, provides now times for stress with the animals. A well furnished aquarium, however, calms the animals very much.

It must be fed in a varied manner. A vitamin preparation should be added to the food more often. The water load must be kept as low as possible by frequent, large-volume water changes.

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Oodinium pillularis is the causative agent of the very common pillularis or velvet disease. Oodinium pillularis is a plant host (Dinoflagellata) of small size. Some members of the genus Oodinium are widespread obligatory skin parasites in fish, especially in aquarium fish. Oodinium pillularis is the best known representative.

The parasitic stage on the fish skin is on average only 0.02 to 0.15 mm long when fully grown. The unicellular, pear-shaped parasites, with a bottle-neck-like thinned part attached to the ephitel, are grayish white to yellowish brown and usually united in small groups.

How is Oodinium pillularis spread??

When the growth on the fish is completed, the parasite detaches and falls to the ground. Then it balls off. Forms a cyst envelope. As with Ichthyophthirius, several divisions follow each other quickly. This produces motile tiny stages corresponding to the Ichthyophthirius hawkmoth, the dinospores. With the help of a ring and drag host, these swarm through the water rotating and rocking slightly in search of a new host.

The life span of the free dinospores is quite short, they must be able to attach themselves to the fish skin in the course of a day or perish. On the fish skin they transform into the pear-shaped parasite and grow in a short time. Oodinium pillularis can also penetrate into the connective tie and cause inflammations here.

Signs of disease

A strong infestation with Oodinium pillularis can be recognized as a yellowish skin coating, which can be dissolved into numerous small nodules on closer inspection, or at least with a magnifying glass. The animals chafe on stones and leaves and often have jammed, frayed fins. The skin may occasionally detach in filaments. Food is usually consumed normally, young animals do not continue to grow, adult animals become emaciated. There is almost never a sudden mass death, but it is characteristic that individual animals die at intervals.

Microscopically the parasites can be detected best on cut fins. They are easily recognizable as oval, yellowish formations, which are almost always in groups, on the transparent fins.

Control of Oodinium pillularis

All fish in an aquarium must always be treated, even if they show no symptoms of the disease. Unfortunately, the treatment is not always successful, so that the disease breaks out again after a short time. In addition to a variety of remedies available commercially, one can also resort to home remedies that have been successfully used by many aquarists.

First of all permanent baths with Trypaflavin, which is available in pharmacies, should be mentioned.. The dosage here is 0.6 g per 100 l of water. This is done by mixing the trypaflavin in a small amount of water and then adding it to the tank, where it is evenly distributed either by aeration or by stirring. Before adding the medicine, the tank temperature should be raised to 30 °C within one day. The treatment period must be at least 14 days. It is best if the filter is switched off and only aeration is in operation, as some filter media filter out the trypaflavin. Otherwise it is necessary to re-dose.

Another treatment option for Oodinium pillularis is the addition of salt with a simultaneous increase in temperature, which is described in Ichthyophthirius multifilis. However, the dosage of 1g/l is usually not sufficient for Oodinium pillularis. Here you often have to add up to 5g/l salt. However, then the plants usually die completely.

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The Fish tuberculosis is a characteristic disease of warm water fishes. About 60 – 80 % of all ornamental fish can be considered infected today. The contamination is strongest in overpopulated community aquariums. But also in the sales tanks of breeders and dealers, which are often densely stocked with numerous species, the transmission of the pathogens is favored in many cases.

At the beginning the fish tuberculosis was misjudged as the aquarium fish ichthyophonus. This is due to the fact that the clinical picture of fish tuberculosis is partly reminiscent of the real Ichthyophonus disease of trout.

The strong spread of the disease is mainly due to the following facts:

– Most of the infected warm water fish do not show any symptoms at first – Almost every treatment method has been unsuccessful so far.

Fish tuberculosis is caused by bacteria – aerobic, sporeless, acid-fast, gram-positive, immobile rods. The life optimum of the pathogens is around 25 °C, d.h. just in the range, which is also necessary for tropical ornamental fishes. The pathogens find optimal conditions in the warm water aquarium, as it were. In principle, all organs of the fish can be attacked, but the density of infestation of the individual organs usually decreases in the order liver, spleen, kidney, heart, skin, eyes, ovary, intestine and skeleton.

Symptoms of the disease

– abraded body due to strong, acute infestation of internal organs, especially the liver (scaly grapes are also possible) – emaciation (knife back, hollow belly) despite good feeding, more or less sudden refusal to feed in the case of long-lasting disease – bump-like elevations on the body, loss of fin parts and whole fins due to ulcers at the fin root (often at the caudal fin) – dark discoloration and grainy deformation of the iris (first signs in angelfish); goggle eyes and ulcerated destruction of the eye in case of severe infestation – appearance of black spots or total dark coloration (in cichlids) – rare symptoms: The animals lie sideways, head and tail somewhat bent up, on the ground and are able only briefly, swimming in an undirected manner, in case of swim bladder damage also staggering movements. Nervous rocking movements with applied fins or temporary lateral position in case of brain damage. Sex reversal in tooth carps due to infestation of the gonads.

The disease symptoms themselves can be extraordinarily diverse and are z.T. determined by the location of the disease foci. In the internal organs, yellowish-white to dirty-grey nodules, so-called tubercles, develop as a result of the confrontation between the host and the pathogens. The host tries to encapsulate the disease by forming more and more new shells. The nodules usually disintegrate from the inside to the outside. Often show deposits of black or yellow pigments. New daughter nodules often develop from the nodules like a hernia sac.

Course of the disease

As the disease progresses, various organs may become dysfunctional or even unable to function, resulting in death. However, it often takes several years until the chronic course is ended by acute symptoms. In addition to the nodules in the internal organs, external symptoms of the disease may be absent or, depending on the location of the focus of the disease, may be quite different.

Transmission of fish tuberculosis

The transmission of fish tuberculosis is possible in many ways. Thus, the pathogens can be expelled with the intestinal contents, with scraps of skin and fins, from broken ulcers and ingested by healthy fish with their food. A particularly strong infection occurs when infected ornamental fish die unnoticed and then serve as food for the living ones.

The bacteria travel from the intestine to the various organs. The susceptibility is in tetras. Especially large in labyrinth fish.

Determination of fish tuberculosis

If fish tuberculosis is suspected, it is best to examine the liver and kidneys. With a simple magnifying glass, even with the naked eye, whitish to yellowish nodules can be seen here. For microscopic examination a piece of an organ is carefully flattened. Tubercles can be easily detected even in dead animals.

Cure of fish tuberculosis

At present, fish tuberculosis cannot be reliably cured. All methods given so far do not lead reliably to success, are often even harmful to the fish. Initially, one has only the possibility to reasonably counteract a further spread of the disease. The following measures are necessary:

– give the fish optimal living conditions so that the disease does not break out in the first place – varied diet, sufficient space and good water hygiene – fish with external manifestations that indicate fish tuberculosis should be removed immediately. Fish showing signs of fish tuberculosis should never be used for breeding purposes – Fish that have been associated with animals suffering from fish tuberculosis must not be given away or sold. They must be well cared for and kept isolated from other fish – in breeding facilities, diseased stock must be completely destroyed (aquariums must be thoroughly disinfected with potassium permanganate (1g/l) or other agent).

Normally the Fish tuberculosis not transmissible to humans. However, people with sensitive immune systems can contract z.B. become infected with the pathogen via small skin lesions; this infection usually manifests itself locally as a so-called swimming pool granuloma (bathing dermatitis).

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Ichthyophthirius multifilis (white spot disease), also called Ichthy, is a common parasite in aquarium fish. It becomes so large (0.3 – 1mm) that it can be seen with the naked eye as a whitish nodule. Infestation of aquarium fish with this parasite therefore does not remain hidden for long, therefore control of the disease can begin at an early stage.

The parasite itself is spherical and covered by numerous cilia with which it rotates. Ichthyophthirius multifilis is a ciliated infusor. Related to the large heart-shaped skin thrush (Chilodonella).

How is Ichthyophthirius multifilis spread??

a diseased fish introduces Ichthyophthirius multifilis as small unnoticed pathogens. Skin Ichthyophthirius, as this stage is called, does not sit on, but in the skin, with preference between epidermis and subcutis. Here it moves in a small, self-drilled cavity and feeds on components of the skin and blood. In the course of 1-2 weeks the parasite grows up. The large, fattened parasite leaves the fish, sinks to the bottom and surrounds itself with a shell, d.h., it encapsulates itself.

In this soil stage, multiplication takes place. In a short time, 250 to 1000 daughter parasites are produced by asexual division, which soon move violently in the cyst envelope. After 15 – 20 hours they leave the cyst shell as swarmers.

In the 3. stage, the hawkmoth must quickly find a fish, because its life in the water is very limited. With its pointed end the hawkmoth bores through the epidermis of the fish. Subsequently transforms into the typical skin ichthyophthirius. In case of heavy infestation, several animals may meet each other while boring into the skin. Then lie together in a cave. In addition to this typical cycle, there are others, such as z.B. The formation of permanent cysts, a division without cyst formation u.a.

Signs of disease

Typical signs of disease in Ichthyophthirius infestation are small, grist-like nodules especially on the fins and in the gills but also in other parts of the body, even in the eyes. The nodules are up to 1 mm in size, whitish in incident light, gray in transmitted light. The distribution of the nodules is irregular, dense groups occur just as frequently as isolated parasites.

In case of very severe infestation, many nodules may be united and the skin may bulge like a sac. The fins are often jammed. The fish themselves may be agitated, rubbing against plants and stones, breathing convulsively and rocking in the advanced stages of the disease. The parasite can be found in the skin-. gill smear easily detect.

Control of Ichthyophthirius multifilis

Even if only a few fish in an aquarium are infected, all fish must be treated. The sooner Ichthyophthirius multifilis is treated, the higher the chances of cure. In the specialized trade there are the most different preparations to buy. However, these do not always lead to success.

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