About animals

Description of fish diseases


The emergence of any disease is preceded by three main factors: environmental conditions favorable for the appearance and course of a particular disease, weakening of fish immunity due to non-compliance of environmental conditions with their requirements and increased susceptibility to diseases, the presence of a pathogen.

To prevent disease, it is therefore necessary to exclude these three risk factors. So the first one. It is necessary to create favorable, optimal conditions for the aquatic environment during all periods of growth and development of fish. To do this, you just need to comply with the fish-biological standards of water quality, planting density. It is necessary to carry out technological measures for the care of the pond, to use the most rational methods of feeding fish. Fulfilling all these simple requirements, you immediately cut off the first and second factors of the onset of diseases. You completely get rid of non-communicable diseases, and the risk of infectious diseases is significantly reduced, since in good conditions the immunity of the fish you grow will be high enough to withstand many diseases.

In order to eliminate the third risk factor, it is necessary to destroy or weaken as much as possible all possible pathogens of the diseases in your household and prevent them from appearing from others in the future. One of the main ways of the occurrence of mass diseases in the economy is the importation of carriers (conditionally healthy) or distributors (diseased fish) of infection or infestation. Sometimes it happens that when importing fish seed material or other age groups of fish, pathogens (viruses, bacteria, protozoa) that are almost always present in the body of fish, due to the stress suffered by the fish during transportation and their weakening, begin to develop rapidly and arise mass epizootic is an outbreak of a disease.

1. Always be careful and do not import sick fish from farms that are dysfunctional for one or another disease.

2. Follow the rules for transportation, tightness, and safety precautions described above. This will save you a lot of trouble. The damage to fish farms in the country for various diseases is enormous. It is difficult to accurately calculate, since it is necessary to take into account not only direct losses from the death of fish, but also from under-production due to growth retardation, poor feed absorption, etc. According to some estimates, this damage makes up from 20 to 50% of all produced in the country of fish. That is why it is so important to pay due attention to hygiene measures.

The occurrence of certain diseases depends on the age of the fish. Thus, carp rubella usually appears in the second year of its life, and pike plague affects only producers.

The appearance of certain diseases, especially invasive, contributes to the composition of natural food. The presence of a significant number of intermediate hosts in it contributes to an increase in the number of pathogens. The likelihood of epizootics increases with an increase in planting density, as the likelihood of fish contact and the pathogens transfer to a new host increases.

Many diseases occur at a certain water temperature. Thus, rubella or carp aeromonosis in acute form most often manifests itself in spring or early summer with a rapid increase in water temperature. Some diseases develop on the contrary at low temperatures, for example, chylodonellosis, which affects wintering yearlings of carp.

Fish-reclamation measures that contribute to the prevention of diseases include:

growing fish in polyculture, differing in the nature of nutrition and species immunity,

the fight against overgrowth of ponds,

periodic flying of ponds when fish are not grown in summer,

drying the pond bed with disinfecting it with lime allows you to destroy eggs and cysts of helminths, protozoa and crustaceans, accumulated over a number of years,

periodic liming of ponds by water.

Veterinary and sanitary measures include:

veterinary control of inter-farm transportation,

preventive quarantine of imported fish,

imposition of quarantine on farms unfavorable for diseases,

preventive disinfection and disinfection of structures, fish farming equipment, a bed of ponds,

regular ichthyopathological examination of the farm,

preventive antiparasitic treatment of fish.

Infectious diseases caused by viruses

Spring carp viremia (VVK) - caused by RNA-containing viruses. Carps, white and motley silver carp, grass carp are sick. The disease develops in early spring at a water temperature of 10-14 ° C, lasts for 1-1, 5 months, then when the water temperature rises to 18-20 ° C, the acute form disappears. It is characterized by swelling of the body, irrigation of scales, single- or double-sided exfoliation, the presence of hemorrhages near the pectoral and abdominal fins. Possible fish waste. Reliable treatment has not been developed. However, it is noted that, subject to all the rules and norms of wintering, transportation, as well as antiparasitic treatments, the disease disappears even on farms that were previously unfavorable for spring carrion viremia. Therefore, the main method of treatment and prevention is compliance with the technological standards of cultivation. When the IHC appears, the farm is quarantined. For humans and animals, sick fish are not dangerous and can be eaten.

Viral Branchionecrosis. It affects carp, rarely silver carp and grass carp at the age of yearlings and two-year-olds. It is expressed in painful changes in the gills, as well as in the kidneys, spleen, liver and heart. It appears in the spring-summer period and lasts 1, 5-2 months. The treatment has not been developed. However, under optimal growing conditions, the disease does not occur even in the presence of a pathogen. For humans and carnivores, sick fish are not dangerous.

Diseases caused by bacteria

Bacterial diseases of fish are the most dangerous, since it is extremely difficult to deal with them in the aquatic environment. In fish bred in ponds, cages and pools, the most common pathogens related to the pathogenic forms of bacteria of the genera Aeromonas, Pseudomonas, Vibrio, Mycobacterium and others. However, aeromonoses are most common.

Aeromonosis of carp. This disease has the household name "rubella." One of the most dangerous and common diseases that cause enormous damage to fish farming in our country, especially in the southern regions. It is characterized by inflammation of the skin, irrigation of scales, eyebrows, swelling of the body, hemorrhages, ulcers on the body may have a whitish rim. In acute form, high mortality. In treatment, antibiotics are used (baths, intraperitoneal injections, feed additives), baths with methylene blue. Doses of drugs are given in table. 1. The causative agent of aeromonosis of carp for humans and animals is not dangerous. Fish, if it has a normal presentation, is allowed for use without restrictions.

Aeromonosis (furunculosis) of salmon. It is characterized by the formation of boils in muscle tissue, after rupture of which reddish ulcers appear. In acute forms, mass death is observed. In addition to salmon fish, including whitefish, it is also found in line, pike, perches, many other species and even frogs, which can also be carriers of the causative agents of this dangerous disease. Treatment - antibiotics and sulfa drugs with food.

Carps pseudomonosis. A disease similar in appearance to rubella affects carp, common carp, silver carp, white and motley silver carp from the age of yearlings to producers. The difference from rubella is that the causative agents of the disease are bacteria of the genus Pseudomonas, and that the disease manifests itself in the second half of wintering: from January to March. The waste of wintering yearlings reaches 30-40%, and in some cases - 100%. The treatment has not been developed. However, an important role in prevention belongs to the establishment of the optimal oxygen regime and flow rate of wintering ponds, as well as the prevention of their re-compaction. After a fish transplant from wintering to feeding ponds, the disease stops and does not appear in the summer. Sick fish are not dangerous to humans.

Fungal diseases

Branchiomycosis Acute infection, which affects carp, carp, crucian carp, gudgeon, tench, pike. It is characterized by the defeat and decay of gill tissue, which leads to the death of fish. In ill fish, gills are restored only after a year. It occurs at a water temperature of 22-25 ° C, most often with low flow and excessive pollution by organic matter. The treatment has not been developed. Good results are given by cessation of feeding, increased water exchange and the use of aeration on ponds.

Saprolegniosis of fish and caviar. It is characterized by damage to the skin, gill apparatus, fins, caviar, on which thin white threads first appear, and then a clearly distinguishable whitish coating. In case of untimely processing, fish and caviar may die. Treatment - baths with salt, malachite greens, methylene blue.

Staffoff's disease. A kind of saprolegniosis. Only mushrooms affect the nasal cavity of fish. On the surface of the head between their eyes and mouth are found either whitish fluffy tassels, or “cotton flakes”. The disease occurs only in winter in wintering yearlings and two-year-old carp. The treatment has not been developed. Prevention - compliance with technological standards during wintering of fish.

Protozoa diseases caused by protozoa

Among the pathogens of fish diseases, related to the simplest - unicellular animal organisms - there are over 500 species that parasitize freshwater fish. Many of them are extremely dangerous and can cause massive death of fish.

Chylodonellosis. Caused by ciliary infusoria chylodonella. It is characterized by damage to the gills and skin, on which a bluish-gray coating appears. It appears mainly in wintering ponds and pools at a water temperature of 4-8 ° С. Treatment. Antiparasitic treatment of diseased fish is carried out directly in ponds with sodium chloride, malachite greens.

General information

In general, fish diseases fall into three broad categories:
Infectious. They are caused by various simple organisms:

  • bacteria
  • fungi
  • viruses
  • seaweed
  • protozoa and so on.

Invasive. The cause of these diseases is various parasites. Infection can be both systemic and random. In the first case, we are talking about the fact that the fish is a permanent or temporary host of one or another species within the framework of the ecosystem under consideration. The following classes are usually referred to parasites:

Not contagious. Usually, their cause is not related to the activity of other living organisms, but is due solely to negative changes in environmental conditions:

  • any deterioration in the food supply,
  • violations of the hydrochemical composition of the reservoir (salinity, acidity, etc.),
  • temperature changes uncharacteristic for the season,
  • habitat poisoning, etc.

It must be said that the described causes can cause disease in all fish, regardless of the way they live. If we talk, for example, about the Karpovs and their characteristic inflammation of the swimming bladder, then the disease can wait for both wild carp and “home” carp grown in fisheries. Not only that, and some aquarium greenhail belonging to this family is also at risk.

Symptoms of a disease can be very specific. However, in most cases, the clinical manifestations of various diseases are very similar. Usually, any fish disorders lead to a violation of their water-salt metabolism. In this case, the symptoms will be approximately as follows:

  • blooming eyes
  • bloating of certain parts of the body (dropsy),
  • rashes
  • raising scales and so on.

Naturally, these signs are not enough to unambiguously and accurately determine any specific disease, but this is a good argument to conduct a diagnostic procedure for fish with the participation of specialists and the use of special tools.

The danger of fish diseases to humans

Fish can be a source of disease for humans and any other warm-blooded animals (cats, dogs, etc.). The most common diseases caused by contact of fish with these organisms are helminthiasis, opisthorchiasis and diphyllobothriasis. All of them can sometimes cause serious poisoning.

Prevention of most of these manifestations for humans is quite simple - it is a thermal or chemical treatment. In the first case, conventional cooking is used, for example, boiling or frying fish. For example, in order for the tapeworm larvae to die in a fish fillet, it is enough to treat it with a temperature above + 55 ° C for 10-15 minutes.

An alternative is freezing. If a fish weighing about 1 kg is placed in the freezer for 10 hours, the same tapeworm larvae will die and will not be dangerous.

For guaranteed disinfection of fish from any parasites, it must be kept for 3 days at a temperature of -20 ° C or for 20-30 days at a temperature of -8-10 ° C.

By chemical treatment is meant simple salting. It is believed that with a salt content of 12-15% by weight and salting time of at least 5 days, the parasites are completely neutralized. Any preservation of fish is possible only after its thermal or chemical treatment.

Now consider in more detail the description of the most common diseases of freshwater fish.

The main diseases of aquarium fish

Aquarium fish diseases are contagious and non-contagious. Non-communicable diseases are caused by adverse environmental factors (improper temperature, poor feed quality, etc.). Infectious diseases provoke pathogens that spread rapidly in the enclosed space of the aquarium and can cause the death of all its inhabitants.

Infectious diseases are divided into infectious and invasive. Infectious diseases are diseases in which pathogens are bacteria, fungi, viruses, and invasive ones are provoked by animal origin. A detailed description of common diseases of aquarium inhabitants with photos and methods of their treatment will be given below.

You can find more information about major diseases in the video.

Contagious diseases

As mentioned above, infectious diseases are provoked by the pathogen (bacteria, fungus, etc.). Depending on the type of disease, the characteristic symptoms of the pathology also appear.

In order to diagnose the disease in time and carry out the correct treatment, you need to know certain signs of popular diseases and be able to fight them.

Fin Rot: Treatment

At the initial stage, it manifests itself in a slight bluish-white clouding of the edges of the fins and sometimes the cornea of ​​the eyes. Gradually, the ends of the rays of the fins begin to fall away, their edges become disheveled (Figure 1).

Note: In young individuals, the tail fin completely disappears. At the base of the destroyed fins, ulcers appear, the spinal column is exposed and the pets die.

The cause is an infectious disease that destroys the fins. The role of the pathogen is a stick. The disease develops due to poor care, as well as with a rare change of water. The disease affects the labyrinth, neon species, as well as angelfish and barbs. Most fry are affected.

Figure 1. Signs of rot of fins

To stop the disease, it is necessary to improve the maintenance of pets.With a severe lesion of the fins, medications should be used. For example, you can arrange therapeutic baths in a separate container. It is also necessary to regularly disinfect the aquarium, soil, equipment. Treat plants with bicillin-5.

The disease appears after a lot of stress or in a crowded aquarium, where the conditions are poor. To prevent the emergence and reproduction of the disease, you must adhere to optimal conditions.


When an individual is affected by a disease, the coordination of movements is impaired, they slowly swim, sometimes lie at the bottom, move spasmodically. Loss of appetite and bulging eyes. With a severe lesion, the eyes are destroyed, the scales rise, the fins tremble, the color darkens, ulcers, dead spots appear. Sometimes external signs may not be present or they are barely noticeable (Figure 2).

Figure 2. Symptoms of ichthyosporidiosis

Infectious disease, the causative agent of which is a fungus that is constantly in the cyst. In it, parasites multiply and fall into the surrounding tissue. The fungus can appear in all tissues and organs, except for bone and cartilage and skin. The fungus enters the aquarium with plants and soil, with fish, mollusks living in open waters.

Note: The disease appears and proceeds slowly, death occurs from exhaustion and atrophy of internal organs.

This disease is contagious and cannot be cured, therefore, affected individuals must be killed. The remaining are transferred to a quarantine aquarium for observation. The container in which the infected individuals were located is well disinfected. Plants are thrown away or disinfected. Inventory and soil must be boiled.

Among the means of prevention can be identified a thorough examination and preparation of feed. For example, marine food is necessarily warmed up, since high temperature destroys the fungus. Healthy individuals must not be allowed to eat the dead, as it may contain parasites.


At the initial stage, the signs of the disease are poorly expressed: the individual is located near air bubbles, wipes off against plants, stones, soil (Figure 3). If you direct rays of light at it, you can see the matte areas. Over time, the body becomes covered with white coating, mucus and pale color appear on the gills. The appetite disappears in the individual, breathing quickens, the reaction slows down and it dies, turning on its side.

Figure 3. Trichodinosis in aquarium fish

The causative agent of trichodinosis is round-ciliary infusoria, reddish in color. It enters the aquarium from a reservoir where fish are found, with plants and soil, if it is not boiled. The parasite lives on the skin and gills.

When the disease manifests itself, individuals are moved to a quarantine aquarium, aeration is carried out with the addition of methylene blue. In an aquarium without fish, ciliates die in 2-3 days. In the future, for prevention, it is necessary to strictly observe the rules of hygiene and move all new individuals to quarantine before moving to the rest.


The specimens are depleted, while their appetite is normal, the anus is inflamed, and sometimes the rectum and bladder fall out (Figure 4).

Figure 4. Signs of hexamitosis

Infection occurs in the stomach, the intestines and gall bladder are affected. It enters the aquarium from a reservoir where salmon fish live. If treatment is not started, the individual dies.

Sick pets are transplanted into a quarantine aquarium and the temperature is raised for two days by turning on aeration. A very depleted individual with a tucked up stomach is killed.


Patients lose their appetite, they lack oxygen, they rise up and gasp for air (Figure 5). On the gill leaves, point hemorrhages appear, the gill covers are deformed. Bright red, blue and pale patches are visible on the gills. With a severe defeat, the fish swims on its side and so dies.

Figure 5. Symptoms of branchiomycosis

Pathogens are fungi that settle on gill petals. All freshwater species with a poor content are affected. High temperature, organic compounds of dead algae contribute to the development of the disease. The disease develops very rapidly, weakened individuals are especially affected.

When the first signs of all the pets appear, they are transferred to a quarantine aquarium and treated with malachite green oxalate, and the viewing one is cleaned and disinfected.

In order to prevent the appearance of branchemycosis, you need to monitor the cleanliness and hygiene of the aquarium.


A sick individual swims sideways, pineal-shaped protrusions, tumors and spots appear on the body, sometimes there is puffy-eyed eyes (Figure 6).

Figure 6. Glugeosis of aquarium inhabitants

Sporonics, which are colonized on tissues, internal organs, and gills, act as a pathogen. Sick fish and plants are destroyed. The aquarium and all accessories must be disinfected.


First, you should evaluate the safety of the reservoir itself. The watch should be abundant flowering of aquatic plants and algae, unusual color, odors, especially the smell of rotten eggs in the summer. Next, carefully look at the pond and evaluate the overall behavior of the fish.

When she is sick, she floats on the surface, does not react to the angler and other objects, or makes abrupt chaotic movements, or swims in circles and jumps into the air. All this is suspicious, you cannot eat such fish. Better yet, go to another body of water. If there is none of the above, then inspect the freshly caught fish, smell it. If odors are mixed in, give it to the cat or follow the catch-let-go principle. All the time remember that the fish accumulates in itself all the toxic elements that are in the pond.

Next, inspect the eyes of the fish. If they are cloudy, with a damaged cornea, dark, then release it too. The eyes of a healthy fish should be bright, convex, with a transparent cornea. The scales should be smooth, shiny, without sticky and badly smelling mucus, to separate with difficulty. If it is ruffled, easily crumbles, does not shine, there are bald spots, then it is better to send this fish back to the reservoir. The gills of healthy fish are scarlet. They should not have any smell, except fish, to be with smooth edges, without dots and blisters on them. The meat of a healthy fish is dense, when pressed, there should not be dents. The color of meat is characteristic of fish of this species and can not be any other. Individual meat fibers should not protrude and stand out. The belly of a healthy fish cannot be swollen. Fins are mostly intact, without rotten rays and any stains.


Here are the most common and most unpleasant signs of sick fish. Abscess abscesses appear on the body of such a fish, in the center of them an elastic greenish-brown rod with a length of about 1 cm comes out. This is a parasitic crustacean that causes lerneosis. Such abscesses are found in crucian carp, tench, pike, burbot, carp and silver carp. Black spots, randomly scattered throughout the body of cyprinids, are also dangerous. These are signs of dangerous helminths. Such fish should not even be thrown back into the reservoir, it is better to burn it at the stake. If the body of the fish is covered with a cotton-like coating and whitish fibers are found on the gills, fins, and nasal openings, it means that it is affected by saprolegnia. Often the fish infected with this fungus lacks fins, scales, and damaged eyes. Saprolegnia also affects eggs, larvae and leads to the death of fish. All of these diseases for humans are not so dangerous, especially if the fish is properly processed. Unfortunately, far from always signs of sick fish are striking. There are helminthic diseases of fish that are very dangerous for humans, which do not appear at all.


In order to protect yourself and loved ones, you need to properly heat the fish during cooking. Thick pieces should be fried for at least 15-20 minutes. A piece should not be thicker than 3 cm. Fry fish cakes (or steam) for at least 20 minutes. Cook the fish from the moment of boiling for at least 15 minutes. All kinds of salting and smoking, and even more so “Japanese” sushi and rolls are more dangerous, since they do not guarantee the death of parasites. If you nevertheless salt or dry the fish, it must be salted out for at least five days, and then dried for two weeks. You can’t even try before! By the way, no fish can be tasted raw or in the cooking process. The same applies to minced fish, caviar and fish semi-finished products. It is safe to eat salted fish only after two weeks. In the freezer at -20 ° C, parasites die in about a week. And remember that freshwater fish of our reservoirs are especially dangerous, marine fish are less dangerous.


Infectious diseases are a group of diseases caused by the penetration of pathogenic (pathogenic) microorganisms into the body. For a pathogenic microbe to cause a disease, it must have virulence, that is, the ability to overcome the body's resistance. This group has an incubation period, that is, a period from the time of infection to the appearance of the first signs of the disease. Infectious diseases are caused by viruses, bacteria and germs, algae and fungi. These are contagious diseases, and if you caught such a fish and identified the disease, then you do not need to release it back into the reservoir. You can inform the local fish protection authorities or the owners of the “payer”.


Rubella, or aeromonosis of carps. This common infectious disease that affects fish can often be found both in natural reservoirs, in ponds for paid fishing or in your pond in the country. It is caused by the bacteria Aeromonas. The acute form is found in spring. It is characterized by dropsy, ruffling of scales, buccal eye, hydration of muscle tissue and all internal organs and is accompanied by high mortality. A chronic or ulcerative form is observed in the summer, accompanied by the formation of characteristic ulcers of a dark red color with a bluish rim.

A sick fish is inactive, keeps off the coast near the surface of the water, weakly or completely does not respond to external stimuli, then it has a disorder of coordination of movements, and the fish dies within two to four weeks. For humans and pets, the disease is not dangerous. Treat fish with antibiotics. Ponds are prevented and try to grow forms of carp that are resistant to this disease. In natural reservoirs, fish are not treated at all. This common disease is recorded in all countries of Western and Eastern Europe, in the reservoirs of South America and in India. It should be borne in mind that this is a bacterial disease (and not a viral one) and it is very difficult to fight bacteria under water conditions.

The next bacterial disease is salmon aeromonosis. This infectious disease is characterized by the appearance of boils in muscle tissue, followed by their rupture and transition to reddish ulcers, significant changes in internal organs, the rapid development of pathological processes and mass death of fish. The disease is characteristic of brook and rainbow trout and, in general, for all species of salmon fish that live in natural reservoirs. It is also registered in whitefish, linea, carps, pikes, perches and even frogs. Most often, fish older than two years get sick. The peak of the disease occurs in spring-summer, when the temperature of the water rises. Under natural conditions, fish are infected through infected water and in other ways. Often the death of fish occurs within four to five days after the bacteria enter the bloodstream. First of all, more fatty individuals die. Fish become sluggish, stay at the surface of the water along the coast, do not accept food. The skin sometimes takes on a dark color. Spotted hemorrhages appear on the skin and gills, as well as at the base of the pectoral fins. They treat the disease with sulfa drugs and antibiotics. For humans, the disease is not yet dangerous (although microbes mutate and it is possible that another Aeromonas mutation will be pathogenic for humans as well). People are unlikely to eat sick fish, it looks very unappetizing.

Another bacterial infection - salmon hemophilia, or peptic ulcer disease of trouts and char, is characterized by the formation of whitish blisters on the body, which subsequently burst, and then open ulcers and wounds arise. The inter-fin membranes are destroyed, the abdomen is bloated and the eye is bulging. Scientists conducted experiments and tried to infect frogs and moon fish with this disease. But nothing came of it: the bacterium is dangerous only for salmonids. However, 100% and very fast mortality make this disease very dangerous for salmon populations. For humans, it is not dangerous, but again, do not forget about the possible mutation of bacteria. Carps pseudomoniasis - a rubella-like disease of carps - is manifested by general dropsy, scaly erosion, buccal eyes and focal hemorrhages on the skin and fins. It is registered in our country, in Western Europe, in China, Israel and other countries. Most often sick year-olds and two-year-olds of different cyprinids. Outbreaks most often occur from January to March and are accompanied by mass death of fish. Sick fish are oppressed, do not respond to external stimuli, approach the surface of the water near the hole and look for an influx of fresh water. Weakened fish are drifted by the flow until they push somewhere or cuddle. For humans, the disease is not dangerous. There are also separate similar diseases: pseudomonosis of cupids and pseudomonosis of silver carp.


Carp bladder inflammation (aerocystitis) occurs in early July. The causative agent is not exactly known (presumably some kind of virus). The infection is transmitted through direct contact of sick and healthy fish, as well as through water and soil. Most often, carp, common carp and other cyprinids are sick. The main symptom is damage to the walls of the swim bladder. At the same time, other nearby organs become inflamed. Fish of different ages get sick, yearlings of carp often die during wintering. Often there is mass death. They are treated with methylene blue (a favorite medicine of ichthyopathologists). In fish, immunity to this disease is possible (especially if they have been ill previously in a mild form).

Branheonecrosis, or gill necrosis Is a viral disease of fish. Very dangerous due to the mass death of all fish. Most often occurs at the beginning and in the middle of summer, and fades out by autumn. Mostly annual and two-year-old carp become ill. It resembles a fungal gill disease.

The fish is oppressed, inactive, keeps near the surface of the water, swallows air, does not respond to external stimuli. Gills inflamed, swollen, mucous, dark red or purple, with foci of hyperemia and hemorrhage. Often begins in dysfunctional reservoirs with a high content of nitrogen compounds (due to fertilizers draining from the fields). The disease is not treated. For humans and animals is not dangerous.

Chum reoviral disease. All six species of Far Eastern salmon are affected. Outwardly, the disease is indistinguishable, only the liver looks painful. The death of manufacturers and the contagiousness of this disease are very high. For humans, it can only be dangerous during spawning. But salmon fishing is prohibited at this time.

Lymphocystis. This disease affects many freshwater and marine fish. They have hypertrophy of the connective tissue cells of the skin. The disease is common in coastal waters of the North, Baltic and Barents Seas. She is ill with 50 species from 20 families. Previously, the disease affected most flounders, but now all the fish in a row.In the initial stage of the disease, all fish look as if they were coated with semolina or bran. Then the white dots increase and become like warts that are already hanging in clusters. Muscles in fish do not grow, their cells are atrophied. As a result, fish growth completely stops, while its death is often not observed. For humans, the disease is not dangerous.


Saprolegniosis and achliosis (dermatomycosis). These are one of the most common fish diseases. Usually they arise not from scratch, but appear either after an injury, or after other infectious diseases. Freshwater fish of almost all types are ill. The skin, fins, gill apparatus are affected. The disease is common in Eastern and Western Europe, in Asia and America. The causative agents are the inferior fungi of saprolegnia and achilia. Fish of all ages are affected, but most often cyprinids under wintering, as well as fish living in bodies of water with poor oxygen and chemical conditions, starving, injured, or suffering from something else. By the way, if you place the pathogen in a safe reservoir with healthy well-kept fish, then the fish do not get these fungi.

In the initial stage of the disease, white thin filaments appear on the skin, fins or gills, perpendicular to the surface of the fish’s body. A few days later, a cotton-like plaque consisting of intertwined hyphae is clearly visible at the site of the fungus's settlement. Fungus hyphae are introduced into the tissues of the skin, muscles and gills and cause atrophy of these organs and even necrosis. Then the hyphae penetrate the internal organs and cause general mycotoxicosis (mycotoxicosis, toxemia - poisoning) of the fish. Sick fish outwardly all as if shrouded in white or yellow cotton wool. Often severely affected fish die. The disease is treated with salt baths, methylene blue, malachite green (green). But in natural reservoirs such treatment cannot be carried out. A person affected by saprolegny fish is better not to eat, although there is no direct threat to health.

Staffoff's disease - This is a type of saprolegniosis in which the nasal cavities of fish are affected, most often in carp. With the development of the fungus, the mycelium leaves the nasal fossa and in the form of fluffy brushes or cotton flakes covers the surface of the fish’s head between the eyes and the mouth. The fish becomes lethargic, keeps near the surface of the water and soon dies. Sometimes hyphae penetrate the meninges. Most often this occurs during and after wintering. A person is not recommended to eat such fish.

Saprolegniosis of caviar. Fungal infection of eggs occurs both during factory incubation and in nature. Aquarists are well aware that caring cichlids and some other fish constantly create a current of water in their fins around their eggs. This is a kind of prophylaxis for the defeat of saprolegnia, which does not like the influx of fresh water rich in oxygen. The disease is recorded in almost all countries with developed fisheries and fish farming. On the affected calf, first appear single point filaments - hyphae of the fungus. Growing up, they cover the eggs with a continuous layer, which looks like a small ottoman or ripened dandelion. Initially, not fertilized, injured, as well as physiologically defective eggs with an insufficient supply of nutrients (yolk) are affected. Saprolegnii appear most often on the eggs of spawning carp and salmon fish in spring and autumn, but caviar of fish of other species is at risk.

Ichthyosporidiosis - ichthyophonosis, or drunken salmon disease. This fungal infection of many freshwater and marine fish is characterized by damage to the internal organs, central nervous system and other fish tissues. The disease was discovered 150 years ago in trouts in Germany. Symptoms are very diverse. When the fungus affects the nervous system, the coordination of movements is disturbed. Sick fish lose their ability to normal movements, it randomly and languidly swims along the coast, convulsions occur. When the gills are affected, suffocation occurs, while outwardly the fish seems healthy. If the mushrooms settled in the kidneys and liver, there is eyebrows, ruffling of scales and the accumulation of exudate in the body cavity - the fish is inflated. When a mushroom infects a swimming bladder, the fish cannot stay in the water column and lies at the bottom. When the fungus enters the muscles and skin, the fish is greatly weakened, and soon the whole body becomes covered with ulcers. The disease lasts more than a year in one individual, so that the mass death of fish does not occur. For humans and animals, this mushroom is not dangerous, but we do not recommend eating such fish. And you can give cats and dogs.

Most of the fish diseases described above, fortunately, do not pose a direct threat to human health.

Ichthyopathologists are involved in the diagnosis and treatment of fish diseases. Before making a diagnosis, scientists give the whole fish or its fragments for analysis, according to the results of which they can accurately establish the disease. The outward signs of many fish diseases are very similar. For example, in freshwater fish with metabolic disorders, the water-salt balance is also disturbed. Outwardly, this is manifested by bloating of the abdomen, a change in behavior, bulging eyes, ruffling of scales and some other signs. So it is difficult for a non-specialist to navigate. That is why fish protection officers recommend that suspicious fish be taken to the laboratory.


If you conduct an ichthyopathological study of fish of any reservoir, you can find in them a certain number of different parasitic organisms. This is a common occurrence. But if the number of these organisms exceeds the threshold value, a disease occurs, which is often dangerous for people who eat this fish for food. It is bad that now, for reasons of economic feasibility, fisheries often increase their density, which causes a sharp jump in the number of parasites.

Protozoal invasive diseases. This group of diseases is caused by the simplest: ciliates and other tiny organisms. There are more than 500 species of protozoa that parasitize on freshwater fish inland water bodies of our country. Unfortunately, it is the protozoa that often cause very dangerous diseases that occur in a severe form and end with the mass death of fish. True, at present, most of these diseases are treated well. Consider specific diseases.

Ichthyophthyroidism - a disease well known not only to ichthyopathologists, but also to aquarists. This is a very dangerous disease of carp, trout, orff, whitefish, peled and many other fish. The causative agent is one of the varieties of ciliates, slippers. The ciliator has a whole life cycle, and fish is one of its links. There is a stage of parasitization in the host’s skin, a stage of reproduction cysts, and a stage of infusoria proliferation in the water. More than 1000 strollers get into the water from one cyst, which become invasive during growth. Touching the body of a floating fish, they cling to it. Most often, fish that have reached the age of four to five years and older are affected. The source of infection is most often sick fish. At the beginning of the disease, the gills acquire a dark cherry color, partially die, and various fungi and other microflora immediately settle on them.

A sick fish behaves extremely restlessly: rushing from one layer of water to another, stirs up silt, swims in a circle, and then sinks to the bottom. Then the fish nails to the shore, and it does not react to anything. The skin comes off with shreds, and when the fish move, it stretches after it through the water. The body is covered with small white dots resembling semolina. There is no direct danger to a person, but doctors do not recommend eating such fish. By the way, protozoa have good adaptability and adaptation, therefore, theoretically, the suitability of the human body for some stage of their life cycle cannot be ruled out.

Kostiosis - An invasive disease that affects the skin and gills of juvenile fish. The causative agent is the flagellate, widely distributed in almost all reservoirs of our country. In natural reservoirs, it is rare, and in ponds - very often. The young of all freshwater and semi-migratory fish is sick. Enzootia (an outbreak of an invasive disease in a particular area) occurs mainly in spring and summer. Healthy fish become infected either from diseased fish or catch a flagellate bone in the water. Cysts can sit in the ground for a long time and wait for the absence of fish or the treatment of a reservoir. And then, when the conditions suit them, prove themselves. This is a disease of thin fish; bone ideally rarely clings to ideally healthy and well-fed fish.

Externally, dull bluish-gray spots first appear on the body of diseased fish, which merge as a pathological process progresses, forming a continuous coating. Necrobiosis occurs in certain areas of the skin, and pathogenic microflora in the form of saprolegnia and achlia settle on them. In an epidemic, boneosis kills up to 97% of the fish. For a person directly, invasion is not dangerous, but doctors do not recommend eating such a fish.

The most common fish diseases caused by protozoa are trichodiniasis, apiosomiasis, scyphidiosis and trichofriosis. The clinical picture of all diseases is similar to the above. For people, these diseases do not pose a direct danger, but it is not recommended to eat sick fish.

Helminthiasis. The most dangerous group of fish diseases for humans is helminthiases. First of all, this is a class of flatworms - monogenetic flukes. Dactylogyrosis is an acute disease that affects gill petals of fish. A total of more than 180 species of monogenes have been found in the fish of our waters. Often, epidemics lead to the mass death of fish in ponds and lakes. This pathogen affects carp fish of all ages, most often an outbreak occurs in June - July. Ill fish behave uneasily, gather on the tributary where there is more oxygen, swallow air from the surface of the water. The disease develops rapidly, occurs literally in a matter of days: from infection to mass death. Outwardly sick fish are exhausted, her eyes are sunken, her gills are covered with mucus and become pale in color. In the damaged areas parasitic fungi settle and gill and other tissues die. Anemia (anemia) occurs.

Tetraonkhoz caused by another monogenetic fluke. Pike and whitefish are affected at all ages and in all regions. The peak of the disease occurs in the summer. Infection occurs through contact with sick fish, as well as with larvae and parasitic carriers that live in this reservoir. In diseased fish, glands appear on the gills, and pieces of gill tissue die. It is difficult to breathe fish, because mushrooms immediately settle on the affected gills. The fish swims at the surface, looking for fresh water inflows, and eats poorly. Often there is a massive death of fish. Monogenetic flukes are not of great danger to humans and pets. But the fish affected by them is so weakened, it has such low immunity that, in addition to monogenes, it also has a bunch of diseases caused by fungi, algae, bacteria and viruses.

The next group of helminthiases is trematodes, or diagenetic flukes. Adult helminths parasitize in the intestines, circulatory and excretory systems of fish-eating birds. And in the tissues and cavities of fish, their larvae are localized - cercariae and metacercariae. Diplostomiasis is a widespread disease. Diplostomes settle in the eyes of fish: in the lens, on the fundus, between the sclera and the retina and cause clouding of the lens and visual impairment. It is difficult to catch such a fish, because it does not see the nozzle. This disease is also called parasitic cataract of fish. Small hemorrhages are visible on the body of the fish, the spine is very curved, the eyes are cloudy and white. Fish swim erratically and randomly, trying to get rid of the parasite, jump sharply out of the water, often land on the shore, where they die. The death of fish occurs when more than 200 cercariae invade it. The disease is not treated. For a person, it does not pose a direct danger, but, as always, doctors do not recommend eating such fish for food.

A similar and very common disease of fish is post-diplostomiasis, registered both in natural reservoirs and in spawning-outgrowths and pond farms. It is characterized by damage to the skin, muscles, curvature of the spine. It manifests itself in the appearance of black spots of various sizes on the body of fish, which gave the disease its original name - black-spotted disease. Spots are formed as a result of the deposition of black pigment in the habitats of helminth larvae. On the skin, they are in various places: on the fins, gills, tail, back, abdomen, sides, cornea of ​​the eyes, on the mucous membrane of the oral cavity, etc. The number of such spots is from several tens to several hundred.

Sources of invasion are infected fish, mollusks and herons, which infect helminth eggs with water. Fish infection occurs mainly in the spring-summer period, which is associated with the development of the pathogen. Freshwater fish such as carp, carp, common bream, roach, grass carp, silver carp, rudd, sabrefish, roach, ram, silver bream, perch, white-eye, chub, podust, etc., are susceptible to post-diplostomosis, more than 60 species in total. Most of these fish are of commercial importance. The most sensitive to the disease are fry and fingerlings. The body of the affected fry is deformed, the spine bends, flexibility is lost, growth is slowed down. Sick fish rise to the upper layers of the water, become weak, and easy to catch.

Another group of diseases - cestodozyr. Caused by tape helminths. The most common and famous name is caviosis of cyprinids. The causative agent is a non-segmented tape helminth of white color, up to 18 cm long, up to 5 mm wide. Its development also occurs with the participation of intermediate hosts - pipe makers. Infected fish with excrement secrete cestode eggs, which fall to the bottom and can be stored in silt for up to three to four months. Fish are infected year-round, but at different periods the disease proceeds with different intensities. In winter, a sick infected fish, without showing signs of the disease, retains the pathogen in itself, where it easily overwinter, and in the spring begins destructive activity.

Sick fish are inactive, keep in shallow water off the coast, skin and eyes are dull, fins are saggy, fish are depleted. Gills and mucous membranes are anemic, abdominal distention and redness of the anus are observed. The death of adult fish is not widespread, and many sick fish continue to live. In humans, this disease has not yet been fixed.

Ligulosis - a widespread disease of carp fish caused by plerocercoids of Ligulidae, large tapered helminths of white or slightly yellowish color, reaching a length of 120 cm and a width of 0.5 -1.7 cm.This parasite is called a tapeworm. Helminths parasitize in the abdominal cavity and cause atrophy of internal organs, infertility, often rupture of the abdominal wall from tension and painful death of the fish. The development cycle in them occurs with the participation of fish-eating birds, with the excrement of which the ligules fall into the water, where they meet new hosts - fish.

The disease is constantly recorded in our rivers and lakes in all freshwater fish. Ligula is quite illegible in the choice of hosts. More often, young fish get sick. Affected fish accumulate in shallow water, in the coastal zone, where it is easier to get food. It is held in the surface layer of water. Swims on its side or abdomen up, while she is still alive. Easy to catch.With a strong wave, such fish can not go into the depths of the reservoir, but are nailed to the thickets, reeds. In places where sick fish accumulate, gulls appear and eat it. The infected fish are exhausted, their abdomen is swollen and hard due to the accumulation of ligules. Settling in the cavity of the body of the fish, plerocercoids grow and reach large sizes. They compress the internal organs, disrupting their functions. Due to the constant and increasing pressure, the liver, spleen, genital glands and other organs atrophy. The metabolic processes in the body are disturbed or sharply inhibited. Infected fish ceases to feed, lags behind in development, is greatly depleted. Sexual gland degeneration occurs and the fish becomes infertile. And worms ligula poison fish with their secretions. Blood counts are changing. There is no cure for this disease.

One of the ways to combat this disease is to plant planktophagous fish, whitefish, pelyad, ripus and zander larvae in water bodies. They eat intermediate hosts - infected cyclops and daphnia, but they themselves do not become infected. And zander eat up the affected small fish. This giant ribbon worm cannot harm a person, but doctors still strongly recommend not eating fish affected by ligulosis. By the way, it is this particular helminth that certain “experts” recommend planting people for weight loss. And they even offered it in a state of cysts in tablets - dietary supplements. It seems to be considered harmless to the body, but at the same time eats calories. Literate doctors from this method are terrified. Unfortunately, there have even been cases of deaths from such Thai pills.

Trienophorosis - the next parasitic disease caused by cestodes by trienoforus (tapeworms). This is a thin white worm reaching a length of 40 cm and a width of 4 mm. Its main hosts in the larval stage are cyclops and daphnia, and fish are already additional hosts. These sexually mature cestodes parasitize in the intestines of pike, perches, omul, grayling and other fish. The most dangerous larval stages of this helminth, which affect the liver, less often other internal organs of trout, perch, pike, smelt, grayling, pike perch, catfish, burbot, ide, trout and many other fish. With parasitic infections, it is especially dangerous to eat the liver and other internal organs of fish. Pets too. Helminths are also localized in the musculature of whitefish and salmon fish, which leads to a decrease in the quality of balyk products. A sexually mature worm secretes eggs in the fish’s intestines that are excreted into the water. Eggs develop in water and soon larvae emerge - coracidia, the developmental periods of which depend on the temperature of the water. The higher it is, the faster the larvae develop. That is, in the summer, infection occurs more intensively - growth occurs from June to August. With intensive infection, a decrease in the body weight of the fish, bloating of the abdomen, pallor of the mucous membranes, and blurred eyes are observed. Young fish die from this parasite. Adults continue to live, or rather exist and support the life support of this parasite and infect water bodies. The treatment has not yet been developed.

The next group of parasitic diseases is nematodosesthe causative agents of which are roundworms of the Nematode class. The most common disease is phylometroidosis of carp, crucian carp and other fish. Mature worms are localized in the muscles of fish, in scaly pockets, less often in the body cavity, and larval stages in the internal organs - liver, gonads, swimming bladder and kidneys. The disease is manifested by inflammation of the liver, swim bladder and is accompanied by general intoxication. Helminths reach 15 cm in length and 1 mm in thickness. Development occurs with the participation of cyclops and fish. The disease manifests itself in May – June. The fry become infected when they reach a weekly age. The initial stage of the disease is characterized by impaired coordination of movement. The fry swiftly and randomly move in the surface layer of water or lower their heads down and make circular movements, which alternate with random movements on their sides, jumping out of the water. Such fry float chaotically and die in two to three days. Death of underyearlings reaches 75%. If yearlings or more adult young fish do not die immediately, then a protracted chronic course of the disease begins. Ichthyopathologists note emaciation, lethargy, anemia, apathy. Fish stays in the surface layer of water, feeds worse. The tuberosity is noticeable on the body, the scales become dull and disheveled, do not shine and disappear. In the affected areas, the saprolegnius fungus immediately settles and other aggravating fish condition appear. Cystopsiosis, which affects exclusively sturgeons, belongs to the same group of diseases. Symptoms of the disease are almost the same as with carp fish phylometroidosis. But it’s not scaly that is ruffled, but ganoid plates with which sturgeons are abundantly covered.

Helminthozoonoses - diseases dangerous to humans!

Most helminths of fish are not dangerous for humans and animals and do not cause diseases in them. However, there are helminths that parasitize in the body of fish in the larval stage, which, once in the human or animal body, cause severe illnesses. Ichthyopathologists and parasitologists call such diseases helminthozoonoses, or helminthic invasions of humans. They are recorded mostly in the basins of large rivers - the Volga, Irtysh, Lena, Yenisei, Amur, Desna, Dnieper, as well as in large lakes and reservoirs. By the way, in developed Western Europe and other civilized states with similar helminthic invasions, the situation is no better than ours. Fish get sick a lot and just as hard. The risk group includes fishermen, since they have direct contact with the ichthyofauna, as well as ichthyologists, fish farmers and fishermen engaged in fishing. It should be noted that freshwater fish are the most dangerous for humans.

Diphyllobothriasis - a disease of humans and carnivores (dogs, cats, foxes, arctic foxes), which is caused by the adult stage of tapeworms - lentetsov. The causative agent is a tape cestode — a worm of white color, from 0.5 cm to 10 m long, up to 1.5 cm wide. The pathogen develops with the participation of an intermediate host (cyclops and daphnia) and an additional host (fish and humans). A person or a dog (cat) infected with this disease secretes parasite eggs into the environment with feces. Once in the water, the eggs develop, and after 10 days a larva emerges - coracidium. These larvae are swallowed by cyclops and daphnia. And already them - fish. Most often this is pike, burbot, perch, ruff, ruff, smelt, peled, vendace, muksun, pyzhyan, chir, omul, grayling. Larvae settle on the walls of the fish’s stomach. In summer, infection occurs most actively, but in winter it is not excluded. Invasion in individual water bodies among fish of species such as pike, burbot, whitefish and others, sometimes reaches 97%. A person or an animal can become infected at any time of the year by eating uninfected fish. Very often, infection occurs when people eat raw caviar of pike during spring fishing. Doctors do not recommend eating all kinds of sushi and rolls in cities. Unfortunately, fatal cases have been recorded after visiting such “restaurants”.

A wide ribbon in the intestines of a person can live 25 years, while a dog, cat or fox can live only a few months. The tape closes the intestinal lumen, thereby disrupting the process of digestion of food and the patency of food masses. Worms secrete toxins that cause anemia, affect the central nervous system. The content of vitamin B12 is sharply reduced. A sick person and animal become agitated and sometimes even aggressive. In infected people, abdominal pain is noted, defecation and appetite are impaired.

Opisthorchiasis - A disease caused by trematode opisthorchis. Mature opisthorchis parasitize in the hepatic bile ducts, gall bladder and pancreas, causing severe liver damage. Larvae - metacercariae - inhabit the muscles of cyprinids. The causative agent, a small trematode, is only 2 mm long and 2 mm wide. But these small sizes do not make it less dangerous for a person than a 10 meter ribbon. In the host's body, opisthorchis lay eggs, which, together with bile, enter the intestine, and from it with feces enter the outside. Eggs develop in water, a larva is formed in them - miracidia. A mollusk swallows it, in his liver the larvae grow, develop and multiply. From there, in the form of cercariae, they go out into the water and cling to fish. In fish, cysts remain inactive for several years. But after eating this fish, a person gets quite active cercariae, which affect his liver and other important organs. The disease spreads focally, most often in large river basins, lakes and reservoirs. Such helminths in humans and domestic animals cause cirrhosis. Doctors sometimes mistakenly treat a person from alcohol dependence. Helminths along with garlic and anthelmintic drugs do not like strong alcohol. Outwardly, a patient with opisthorchiasis is depressed, has a swollen abdomen, and the liver is enlarged and compacted. Patients are restless, they have chills and fever. The mucous eye is yellowish. Such patients should be isolated from society until complete recovery, which today is increasingly being achieved.

Clonorchiasis called trematode clonorchis, which reaches 2 cm in length and 4 mm in width. This is a small yellow-white ribbon, which is difficult to confuse with something else. Helminth parasitizes in the liver and bile ducts, causing cholecystitis, cirrhosis of the liver and other diseases in people, often leading to death, if you do not start treating them in time. Symptoms are similar to the symptoms of a previous illness. However, the host is another mollusk, and the foci of the disease are mainly located in the Far East and in the Amur region.

Metagonymosis causes tremotoda with spines located in the small intestine of a person, resulting in its atrophy. Nanophytosis is also caused by a trematode parasitizing in the small intestine. People infected with these trematodes are emaciated, their skin and mucous membranes are pale, they complain of severe pain in the right hypochondrium, constant weakness, lethargy, lack of appetite and dizziness.

Dioctophimosis. The causative agent of this disease is a large red nematode up to 105 cm long and 5 mm wide. Its intermediate host is the tuber larvae (oligochaetes). Mostly found in rivers and lakes of the Aral Sea basin. Helminth is introduced into the wall of the human stomach, sometimes it enters the urethra. All this causes severe pain and atrophy of the affected organs. In sick people and animals, there is no appetite, vomiting, general exhaustion, and a depressed state appear. A muddy, bloody liquid accumulates inside the renal pelvis, smelling like urine. The mucous membrane of the renal pelvis becomes grayish-white or yellowish in color. Treatment is only surgical; urgent surgical intervention and extraction of dioctophyma from the affected organ is required.

Aquarium Fish Diseases

All fish diseases are divided into three broad groups:

  • Infectious diseases of fish that cause bacteria, viruses, fungi.
  • Invasive fish diseases - invasion refers to the invasion of parasites into the body.
  • Non-communicable ailments, the appearance of which most often provoke improper care or maintenance.

Conventionally, the diseases of the small inhabitants of the aquarium can be divided into infectious and non-infectious. Information about the symptoms of a particular ailment can save the lives of underwater pets, therefore, information and a description of the treatment methods for aquarium fish will be useful for everyone who has an artificial pond.

Non-communicable diseases

Non-contagious ailments are diseases that are not transmitted to other inhabitants of the aquarium. Most often, the development of ailments that fall into this category is caused by improper care or incorrect conditions. Treatment consists in eliminating an adverse factor or parasite that triggered the ailment.


Alkalosis, or alkaline disease of aquarium inhabitants develops due to too soft and acidic aquatic environment, the formation of which contributes to an abundant amount of vegetation and intense lighting. External signs of alkalosis are as follows:

  • The color intensity decreases, the gloss disappears.
  • Fins spread wide, fish behave excitedly and unusual.
  • From the gills, mucus is plentifully secreted.

If measures are not taken to complete medical procedures, the fish may become blind due to blurred eyes and die. For the treatment of alkalosis, it is necessary to transplant sick pets into a container with a pH of 7-8.5, while restoring balance in the old aquarium.


The development of argulosis causes a crustacean, a carnivore, or fish louse. These are quite large parasites with a rounded body shape, which are easy to notice on visual inspection.

In addition, the following symptoms will indicate the appearance of argulosis:

  • A large amount of bloody mucus from the wound from the penetration of the parasite.
  • The patient turns away from food, sways or rubs on hard surfaces.

Penetrating into the body, the carnivore destroys the skin and muscles, and secretes toxins into the body, poisoning the fish. To save the pet, you should pull the fish out of the pond and pull out the parasite with tweezers. After that, the wound is treated with a solution of potassium permanganate.


Acidemia, or ammonia poisoning, is observed among residents of resettled water bodies, where in the aquatic environment there is a large concentration of waste products. Symptoms of ammonia poisoning:

  • The color of the scales darkens, sick fish swims near the surface of the water.
  • In rare cases, gill injuries are observed, the fish tend to jump out of the tank.

To treat the injured, replace half the volume of water, increase aeration and thoroughly clean the tank of dirt.


Acidosis, or acidic disease, develops with a sudden drop in pH. Fish suffering from acidosis become weak and lethargic, white spots form on the body. In the victims of acidosis, the gills are closed, and the dead themselves are folded. For treatment, baking soda is added to the tank to bring acidity back to normal. In the future, it is necessary to monitor the pH, and regularly make water changes.

Gastrointestinal inflammation

Inflammation of the digestive tract in aquarium fish develops due to the use of poor-quality or too hard food. The disease is accompanied by the following symptoms:

  • Tarnishing color.
  • Weakness and apathy.
  • Filamentous bowel movements with blood or mucus.

For treatment, you need not to feed the wards for a couple of days, and then only use a high-quality and balanced diet.

Chlorine poisoning

Chlorine poisoning in fish occurs due to the content in the aquatic environment, where there is an increased presence of chlorine. In case of poisoning, pets feel weak and lethargic, try to jump out, the gills become pale. If you do not take appropriate measures, then the fish die.

To cure the inhabitants, the fish are moved to a tank with a suitable environment. Water should be left to stand for 2 days, and pass through a filter filled with coal.

Gas embolism

Gas embolism in fish is a disease caused by blockage of blood vessels by air bubbles when fish live in an oxygen-concentrated environment. Symptoms of the disease are as follows:

  • Restless and disturbing behavior.
  • Gill tissues darken.
  • The fish eyes twitch in a cloudy veil, swelling appears.

Transplantation of fish into a tank with a normal aquatic environment will help eliminate the disease.


The common cold can develop not only in humans, but also in aquarium fish.The reasons for the occurrence lie in too cool water, as a result of which the pets catch a cold.

Symptoms of a cold are:

  • Lethargy and pallor of color.
  • Fish sway, swim to the surface.
  • Gills swell and darken.

An increase in temperature to the degree required by a particular phenotype will help cure fish.

Mechanical injuries

With incorrectly chosen neighbors, aquarium fish often conflict and enter into fights, resulting in injuries and injuries. In addition, fish may injure themselves against the sharp edges of the scenery in the tank. Having noticed damage to the pet’s body, an unfavorable factor should be eliminated from the reservoir, and serious injuries should be treated with bathtubs with potassium permanganate or methylene blue.

Contagious diseases

Diseases of aquarium fish, included in the group of infectious ailments, are much more dangerous than non-communicable diseases. Many of them end in mass death, as infections penetrate rapidly when they enter the reservoir. In order to prevent the death of the inhabitants of the aquarium, you should be able to recognize the first symptoms of the disease and know how to treat fish.


White-skinned - a dangerous ailment, which is caused by the pathogen bacterium Pseudomonas dermoalba. The pathogenic bacterium enters the reservoir along with infected new neighbors, decorations or plants. With the development of the disease in fish, the following symptoms are observed:

  • Near the tail and dorsal fin, the tissues whiten.
  • Sick fish swims near the surface of the water.

If you do not start treatment, the disease will affect the nervous system and lead to death. For treatment, baths with chloramphenicol are used, and the scenery, plants, substrate in the old aquarium are disinfected.


Gyrodactyles is a contagious disease initiated by a fluke parasite that attacks the skin, fins and gills of a fish. The disease is accompanied by the following external symptoms:

  • A sick fish swims near the surface, sways slightly.
  • The fins are pressed to the body.
  • A gray coating appears on the gills and body of the fish, the fins are destroyed.

For treatment in a species tank, a solution of Bicillin is used; in separate containers, gyrodactylysis is eliminated with a solution of sodium chloride, green malachite and copper sulfate. The temperature of the water during medical actions is increased.

Fin rot

Fin rot is a common disease in veiled-tail phenotypes. When infected, the fins of the fish are covered with a light gray or white-blue coating, then the rays are destroyed and the fins die.

Treatment is carried out with the help of baths with a solution of malachite greens, Bitsillin, and Antipara.


  • The development of ichthyophthyroidism initiates protozoa that affect the skin and gill tissues. You can recognize the disease by the following signs:
    Pets rub against sharp edges and hard objects.
  • Fish swim to the surface.
  • Light marks and spots form on the body of the infected.

In aquarium fish infected with ichthyophthyroidism, the treatment is carried out with bactericidal agents: Bitsillin, Antipar, Bactopur in a separate container. In an infected aquarium, the temperature is increased to 33C for 3 days, replace ¼ of the liquid volume.


With the development of dermatomycosis, the causative agent of which is a fungus, the skin and gills of fish are affected. The disease is easily recognized by the formation of thin white threads on the skin.

Dermatomycosis is treated with baths with Bicillin, solutions of potassium permanganate and malachite green.

In aquarium fish, diseases arise suddenly, so every aquarist should be prepared for such an event. It is useful to know everyone about the symptoms and methods of treating common ailments of aquarium inhabitants, because they helped save more than one fish. Having found that the pets are sick, you need not panic, but act - the sooner treatment is started, the greater the success of the healing.


The infected individual loses its appetite, stays at the surface, eagerly swallowing air, rubs against objects. Her gills are covered with a thick layer of mucus and resemble a mosaic. The adjacent gill petals are fused.

The causative agent of the parasite is a fluke, it lives on gill petals. It enters the aquarium from a reservoir containing fish. Infection is promoted by a dense landing and weak immunity due to poor living conditions. It settles mainly on carp species.

For treatment, individuals are transferred to a quarantine aquarium with the addition of copper sulfate. In a general aquarium, larvae without fish will die during the day. When buying new individuals, quarantine is mandatory. The aquarium is disinfected with a solution of baking soda.


At the initial stage, scales are raised in some places on the affected individual. Gradually, this phenomenon spreads throughout the body. Soon, the scales fall out and the fish die (Figure 8).

Figure 8. Symptoms of lepidortosis

The causative agents are bacteria that enter the aquarium from a reservoir where there is fish with food.

To determine the pathology, a microscopic examination of the pustules and adjacent tissues is necessary. An infected individual can be cured only at the initial stage. Conduct medical baths. If therapy does not help, then the fish are killed, and the aquarium with equipment is disinfected.

Semka in aquarium fish: treatment

With the disease, skin lesions occur, which causes ciliates. It gets on the skin, then penetrates under the epithelium, where it multiplies. It enters the aquarium with food, water, soil, plants, shellfish.

A sick individual behaves uneasily, rubs against plants and soil, is constantly located near the aeration filter. If treatment is not started, the epithelium will peel off in pieces, the fish will go blind, gill capillaries may burst (Figure 9).

Enzyme parasite adversely affect the body of aquatic pets. The disease lasts two weeks. If an individual has successfully suffered an ailment, it develops immunity.

Figure 9. Decoy in aquarium fish

For treatment, the decoys of all individuals are transferred to another container with a solution of biomycin or ichthyophthyricide, the temperature is increased and strong aeration is turned on, observing the behavior of the fish.

Aquarium fish alkaline disease

The main factor in the occurrence of alkaline disease is an increase in acidity, which can be fatal for some species (Figure 11).

Note: The disease can occur acutely with a sharp change in pH, or chronically, with a gradual change in a certain period of time. Alkaline water irritates the outer surface of the body.

Minerals, dissolved in water, increase the acidity of the water, help stabilize the pH, and the metabolic processes in fish have an oxidizing effect that counteracts the increase in alkalinity of water.

Figure 11. Signs of an alkaline disease

If you transfer fish from one aquarium to another, you should remember the level of acidity, otherwise you may encounter acute alkalosis. A suitable pH can be achieved using a pH buffer. To slowly adjust the pH, a partial replacement of water with a liquid with neutral acidity is used.

Sexual cyst

It often proceeds chronically. The abdomen with liquid or semi-liquid contents increases in size due to the tumor. Having started treatment in time, you can save the female from infertility and death.

Note: The cause of the ailment is a long separate separation of males and females, as well as monotonous feeding with dry food.

At the initial stage of the disease, the fish is placed on wet cotton wool and lightly stroking the abdomen so that the contents of the cyst exit through the anus.