About animals

The main diseases of aquarium fish


Diseases of aquarium fish can be divided into two categories: infectious, infectious, caused by various microorganisms and transmitted from fish to fish, and non-infectious, caused by improper conditions or large parasites.

In the first case, treatment of a pet requires the intervention of medications that can destroy the causative agent of the disease. In the second, changes in conditions of detention are often effective, excluding the pathogenic factor, mechanical removal of the parasite, any measures that will strengthen the fish organism weakened by the disease. But almost always poor fish conditions and poor quality food weaken the immune system or are the direct causes of the disease.

Timely diagnosis always facilitates the treatment of any disease of aquarium fish, because almost all diseases are effectively suppressed in the early stages.

Alkalosis or alkaline disease

Reasons: too soft, acidified water in the aquarium, which becomes so with excessive lighting, a large number of plants.

Signs: the color and luster of the fish scales fade, mucus is released from their gills, the movements become convulsive, the fins are spread wide. Fish are trying to jump out of the aquarium. If the disease is triggered, the cornea begins to clouding, followed by blindness, a mass death of the inhabitants of the aquarium is possible, which occurs, as a rule, at night.

Treatment: the transfer of fish to a tank, the water in which has a pH of 7-8.5, will help. In a general aquarium, gradually bring acidity to the desired boundaries. Fish recovery will be slow.


Reasons: parasitic crustacean, carpoed, also called “fish louse”. The crustacean is quite large - we can see it with the naked eye, it is round in shape, so the diagnosis is not too complicated.

Symptoms: getting on the body of the fish, the crustacean invades the tissue, forming a wound with swollen, reddened edges, copious secretion of mucus. The fish itches with an ulcerated place on solid objects, sways in place, her appetite spoils. The crustacean destroys not only the upper layer of the body - the epidermis and skin, but even the muscles. In addition, it releases a substance that slowly poisons a fish.

Treatment: the patient is caught from a common aquarium, wrapped with cotton and tweezers, the parasite is carefully removed. After that, the damaged area is disinfected with potassium permanganate.

Asphyxia or suffocation

Reasons: arises due to the long stay of fish in an oxygen-poor environment. This is possible in a crowded aquarium, tanks with insufficient aeration.

Signs: gills open, fish making intense breathing movements. In case of death, the mouth and gills remain open. Mass death of fish is possible.

Treatment: moving the fish into water that has enough oxygen will help. Changes in conditions in the general aquarium: increased aeration, cleaning of debris, rotting food debris, siphon of soil.

Symptoms may coincide with some infectious diseases. The diagnosis can be accurately made by placing the fish in oxygenated water - if you do not see any improvement, then the disease is of an infectious origin.

Acidemia or Ammonia Poisoning

Reasons: high content in the water of vital products of fish, invertebrates, plants. It appears in overpopulated, insufficiently maintained aquariums, where water is rarely replaced, there are rotting accumulations of organic matter.

Signs: the color of the aquarium pets is getting dark; they are kept near the surface of the water. Possible damage to their gills, attempts to jump out of the aquarium. Symptoms are similar to many signs of other diseases; diagnosis can be difficult. But the aquarist usually understands what mistakes he made in the content of the home reservoir, and if the aquarium is not groomed, then the symptoms indicate precisely ammonia poisoning.

Treatment: first of all - to replace a significant amount of water in order to reduce the concentration of harmful substances. Strengthen aeration, clean the aquarium.

Acidosis or acid disease

Reasons: gradual or sharp decrease in pH. Perhaps with the spawning of fish, the appearance of beginners in the aquarium.

Signs: the fish become lethargic and alert, grayish-white spots gradually appear on their bodies, they begin to swim sideways or belly up. Dead fish curl up, gill covers closed. With a sharp decrease in pH (this happens when the fish are transferred to new conditions), the fish rush about, try to jump out, secrete a lot of mucus. They also die curled up.

Treatment: adding baking soda to the aquarium to normalize the level of acidity, water change, more frequent changes in the future.

Gastrointestinal tract inflammation

Reasons: poor quality food, monotonous or too hard food.

Signs: faded color, lethargic behavior, filiform feces with mucus and blood, inflamed anal opening. Symptoms may be characteristic of some infectious diseases, the diagnosis is not easy, but in any case, treatment - improving food - will help improve the condition of the fish.

Treatment: stop feeding for a few days to allow the mucous membrane of the internal organs to recover, then apply a high-quality, varied food that is easily absorbed.

Sexual cyst

Reason: keeping separately females and males in combination with uniform feeding.

Symptoms: the belly of the fish is swollen, as during spawning - there forms a semi-fluid tumor, pressing on their internal organs. Fish appetite disappears, infertility develops, the fish dies.

Treatment: in the early stages, the disease is almost impossible to detect, and when it is visible, treatment will help little. You can try putting the fish on a cotton swab and, stroking the belly, squeeze the cyst through the anus. But life expectancy and the ability to reproduce after this remain a big question.


Reason: uniform feeding, dry food, overpopulation of the aquarium.

Signs: fish are inactive, upper abdomen is swollen. Blood brightens, adipose tissue forms on the internal organs, which leads to disruption of their work and death of the fish.

Obesity is almost always fatal. Prevention - rational, regular feeding in small portions of various feeds, unloading, without feed, days once a week, sufficient volume of the aquarium for free swimming.

Chlorine poisoning

Reasons: high chlorine content in the water, which happens when the tap water is improperly prepared for a change.

Signs: the fish stay on the surface, may try to jump out of the aquarium, then their gill petals become pale, lethargy occurs, the fish do not respond to irritation and die.

Treatment: transfer the fish to an aquarium with good water. Settle the water from the chlorinated aquarium for at least 48 hours, pass through a charcoal filter. You can quickly get rid of chlorine in water by heating it to 90 degrees.

Gas embolism

Reasons: vessels are clogged with air bubbles if the water is too rich in oxygen. This happens when the tap water is not adequately prepared for a change.

Symptoms: the fish are worried, sometimes tremble, gill tissues darken, sometimes the eyes become cloudy and swelling appears. At the autopsy of the dead fish, foamy blood appears.

Treatment: to improve the condition of the fish, transplant them into water with normal oxygen content.


Reasons: keeping fish in too cold water for their species.

Signs: the fish become lethargic, grow dull, keep to the surface, swaying, fin fins may be pressed, gills darken and swell, immunity decreases and secondary infections become possible.

Treatment: increase the temperature to the optimum for these species will help.

Mechanical injuries

Reasons: fights, aggression of some fish in relation to others, damage to sharp objects (for example, plastic plants, sharp stones). Especially frequent injuries to the fins.

Treatment: minor injuries heal themselves, larger ones should be decontaminated with lotions of potassium permanganate, baths with methylene blue. Try to remove the factor causing injury from the aquarium.


Pathogen: Pseudomonas dermoalba, bacterium. It enters the aquarium along with infected beginners, objects or plants from the container where the disease developed.

Signs: tissues near the caudal and dorsal fins whiten, the fish begins to stay at the surface. Infection affects the central nervous system, coordination organs. It leads to the death of the fish.

Treatment: baths with chloramphenicol will help. The container where the sick fish, soil, plants, and equipment were kept requires disinfection.


Pathogen: Branchiomyces sanguinis and Branchiomyces demigrans, fungi that form blood clots in blood vessels.

Signs: at the onset of the disease, red, dark stripes form on the gills due to clogging of blood vessels. The fish becomes lethargic, it can be caught by hand. The appetite disappears, the patient hides in dark corners, is hunched over, there is a pressing of fins. Later, the gills become "marble" in color with an alternation of pink, gray, whitish stripes. Tissues begin to die. The disease is extremely contagious, diagnosis should be carried out as soon as possible. In just over three days, an infection can take away more than half the population of the aquarium.

They are treated in precipitators with solutions of copper sulfate and rivanol. The general aquarium is disinfected, completely replace the water. Recovery of gill tissues in recovered fish can take up to a year.


Pathogen: infusoria-flagellate hexamite or its variants.

Signs: exhaustion, inflamed anal hole, filiform white mucous feces. Erosion of the skin in the form of mucous perforated ulcers. In the early stages, diagnosis can be difficult. The disease is very contagious, especially for cicholic.

The creation of favorable conditions, a diverse and nutritious feed will help. Medical treatment, antibiotics erythorimycin, griseofulvin, metronidazole are used, dissolving in aquarium water, soaking the feed in the solution. A long course of treatment is 10-14 days. For healthy fish, treatment and prophylactic measures are applied - a course of antibiotics in half a reduced concentration.


Pathogen: Gyrodactylus, parasitic fluke that infects the skin, fins, gill tissue of fish.

Signs: the fish keeps on the surface, sways, the pressing of the fins to the body is characteristic. At later stages, the appetite disappears, the fish rubs against hard surfaces, gray patches appear on the body, the destruction of the fins begins, and a gray coating on the gills appears.

Treatment: in the main aquarium, solutions of bicillin, azipirin will help, in the depositor - sodium chloride, formalin, malachite green, copper sulfate or methylene blue. It is recommended to increase the temperature of the water for better healing.


Pathogen: sporovik from the Microsporidia squad. It affects the internal organs, gills, eyes.

Signs: the fish rests on its side, protrusions appear on the skin, which become tearing tumors of a whitish, bloody color. A bulging eye is formed on one or both sides.

There is no way to help. The infected fish dies, the remaining inhabitants and plants should be destroyed, the soil, scenery, equipment and the aquarium itself should be thoroughly disinfected.

Fin rot

Pathogen: Pseudomonas wand. It is activated in fish subjected to hypothermia. Fish with an elongated or veil fin structure are particularly susceptible to disease.

Signs: whitish with a blue tint clouding of the edges of the fins, sometimes the eyes - at this stage the diagnosis is difficult, usually the disease is noticed by very experienced and attentive aquarists. Then begins the decay of the fins. In juveniles, the caudal fin may completely disappear. If this happens with an adult fish, the destruction will affect the skin, muscles, blood vessels - the fish dies.

Treatment: bactericidal drugs will help. Baths with a solution of Antipara, bicillin, malachite green. Sometimes, in the early stages, self-healing of the fish is possible with improved conditions.


Pathogen: Dactylogyrus fluke that affects gill tissue.

Symptoms: the affected fish loses their appetite, keeps in the aquarium above, rubs against hard surfaces, produces active respiratory movements. Gills turn pale or acquire a mottled color, their petals stick together, mucus protrudes abundantly, the edges ulcerate.

Treatment: it helps to increase the temperature of the water, the introduction of a solution of bicillin, salt, formalin into the water. It can be treated both in the main aquarium and in the jailer.

Dermatomycosis or saprolegnia

Pathogen: Saprolegniales, mold. It affects the skin, gills, sometimes - internal organs. Often a secondary infection is already attenuated by any disease of the fish.

Symptoms: the fungus appears in the form of thin whitish threads on the skin and gills of the fish. In advanced cases, it affects their internal organs and the fish dies.

Treatment: first of all, it is necessary to treat the initial disease, against the background of which the fungus has developed. If the initial disease is absent and the reasons were weakened immunity or improper conditions of detention, then therapeutic baths with solutions of bicillin, potassium permanganate, malachite green, table salt will help.


Pathogen: Ichthyosporidium hoferi fungus. It affects all tissues except bone and cartilage.

Signs: the fish moves irregularly, itches, refuses to feed, may lie on its side. The mouth is open, a bulging eye develops. There are possible eyesore, destruction of the fins, erosion of the skin. In the body of the fish, tumors form, organs cease to function.

There is no way to save the fish. Patients die, the remaining inhabitants should be destroyed, equipment should be disinfected.

Ichthyophthyroidism or point disease, semolina

Pathogen: the simplest Ichthyophthirius multifiliis. It affects the skin and gills.

Symptoms: the diagnosis is very simple - the fish itches on solid objects, keeps on the surface, breathes greedily. Then rashes appear in the body in the form of white dots, grains. Disease can lead to the death of fish.

Treatment: daily administration of bactericidal preparations (malachite green with iodine, bicillin, Antipar, Bactopur) along with a quarter water volume change, gradual heating of water by 4-5 degrees will help.


Pathogen: Aeromonas punctata or Pseudomonas fluorescens, bacteria affecting the skin

Signs: a fish rises in the fish, since pustules are formed under the scales - bubbles filled with liquid. Then begins the loss of scales and the fish dies. Symptoms are similar to signs of tuberculosis, ichthyospiridiosis, accurate diagnosis is possible using laboratory equipment.

Treatment: help is effective at the very beginning of the disease, when the scales are raised only in certain parts of the body. Baths are used and the introduction of antibiotic solutions into the aquarium - bicillin, biomycin, streptocide. The disease is very contagious; treatment and prophylactic measures should be applied to the inhabitants of the main aquarium; If the treatment does not help, the diseased fish should be destroyed, the aquarium equipment and soil should be disinfected.


Pathogen: the simplest Trichodina, which affects the skin. Danger for many common species of aquarium fish.

Signs: at the initial stage, diagnosis is almost impossible, the fish can only rub on hard surfaces from time to time. In the course of development, the color of the fish fades, appetite disappears, areas of a grayish coating appear on the body, which can peel off.

Treatment: raising the temperature of the water, enhancing aeration, and medication will help. In a general aquarium, with solutions of salt, tripaflavin, methylene blue. Warm (up to 34 degrees) baths with sodium chloride, ammonia solution. To rid the aquarium of parasites, you should remove the fish for two days and warm the water to 35 degrees.

Peptic ulcer

Pathogen: Pseudomonas fluorescens, a microbe that affects the skin and intestines.

Signs: the appearance on the fish’s body of dark spots and dots that gradually turn into ulcers, the development of buccal eye, inflammation of the anus and, as a result, intestinal inflammation - a bloated abdomen.

Treatment: help is effective at the onset of the disease. In a general aquarium, a solution of streptocide, biomycin, bicillin is used. Separate and baths contain potassium permanganate and hydrochloride. Aquarium and equipment need to be disinfected.

General rules for prevention

Favorable conditions for keeping the aquarium - timely replacement of properly prepared water, good aeration, regular cleaning of the aquarium eliminates the possibility of a huge number of diseases. A regular diet, which includes a variety of feeds rich in vitamins and minerals, significantly increases your pets' resistance to disease. With rare exceptions, it is good maintenance that is the best prevention of every aquarium fish disease.

You need to be careful to replenish the aquarium - to acquire only healthy fish, carefully maintain quarantine.