Why Do Fish Die In The Aquarium Tank For Beginners

The aquarium is a great addition to the interior and the opportunity to have unpretentious pets that do not require special skills and attention. However, quite often newcomers in this business face the problem of the death of underwater inhabitants. Why do fish die in an aquarium? The answer to this question and give our article.

The most common mistake newbies is the opinion that the aquarium and the fish living in it, do not need additional care. Far from it, because these silent pets need not only periodic feeding, they need light and additional oxygen, and so on.

Why do fish die in an aquarium: reasons

  1. Poisoning with nitrogenous substances.
  2. Incorrect settlement.
  3. Disease.
  4. Low / high temperature.
  5. Unsuitable light in the aquarium or lack thereof.
  6. Improper water quality.
  7. Lack of oxygen.
  8. Aggression from neighbors.
  9. Old age.

Nitrogen poisoning

Nitrogenous compounds appear in water as a result of the breakdown of waste products of its inhabitants, with poor purification. Especially toxic nitrites and nitrates. An increase in their number is accompanied by the appearance of rot smells, the aquarium becomes cloudy. Bacteria that process waste products into the nitrogen compounds described above, settle in filter media and soil. The solution to the problem lies in the proper purification of water, constant use and washing of filters, reducing the amount of food (its residues can also decompose and poison the aquarium).

Why Do Fish Die In The Aquarium Tank For Beginners

Wrong settlement

How many fish can you keep in an aquarium? The number of inhabitants depends not only on their length and build, but also on their behavior. In small aquariums (20-30 liters) is better to keep small thin fish, adhering to the rule: one liter of fluid per centimeter of the length of the animal.

For schooling, aggressive and large pets suitable capacity from one hundred and more liters. Overpopulation threatens lack of oxygen and, as a consequence, the death of animals. An important factor for the full life of the fish is the light in the aquarium.

Proper lighting

Why do fish die? In an aquarium, it is impossible to neglect the lighting in any case. Most species of fish need coverage for 10-12 hours a day, and if it is lacking, they simply become ill and die.

And because the aquarium (for beginners, these tips are especially important) must be equipped with special lighting devices.


If the fish die in the aquarium, what happened, you need to find out as soon as possible. A fairly common cause of the mass plague of pets is their disease, which is divided into infectious and non-infectious.

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The cause of the first group of diseases can be infections (fungi, viruses, or bacteria) and invasions (various parasites). The treatment of such diseases will require the urgent use of drug therapy:

  • White skin. Called Pseudomonas Dermoalba. This microorganism enters the aquarium with new algae, inhabitants or soil. Manifestation of the disease in the form of white bloom on the back and tail of the fish. Infected individuals swim on the surface. The bacterium causes damage to the nervous system and, as a result, impaired coordination. The treatment consists in the complete disinfection of the aquarium (including soil, plants and equipment) and the use of levomycetin baths for the inhabitants.
  • Branchomycosis. The cause of its occurrence is Branchiomyces demigrans (fungus), which leads to the formation of numerous blood clots in the vessels. The disease is highly contagious, and within two to three days all the animals in the aquarium may die. It is very important to determine the diagnosis at the first signs of the appearance of the disease and to begin treatment, which can be delayed for ten to twelve months. Symptoms: the appearance of brown-red lines on the gills, loss of appetite, pressing the fins to the body. With the development of the disease appear pink, white, gray stripes, and the gills become marble colors. Sick fish hide in secluded places. Branchiomycosis therapy is reduced to transplanting diseased individuals into a separate container and using solutions of copper sulfate and Rivanol. The aquarium and equipment is disinfected, and the water is completely changed.
  • Hexamitosis. Caused by infusoria hexamite. The disease is very contagious and especially dangerous for cichlids. The treatment takes one and a half to two weeks. Symptomatology: mucous erosive ulcers appear on the body of the fish, the anus is inflamed, and the feces take on a slimy white thread-like character. Antibiotics (Metronidazole, Griseofulvin, Erythromycin) are used to treat hexamitosis. Before using the above means must be dissolved in water. In the resulting solution is soaked and feed.
  • Gyrodactylosis. The source of this disease is the Gyrodactylus parasite, which infects the fins, gills and skin of fish. Affected individuals are on the surface of the water, press their fins to their bodies and rub against stones and other surfaces, lose their appetite. In the area of ​​the gills and in other parts of the body appear brownish-grayish spots, which are signs of tissue destruction. For the treatment of gyrodactyls, "Bicillin" and "Azipirin" are added to the water. Infected fish are transplanted into separate containers, adding salt, copper sulfate, formalin or malachite green to them. The temperature of the water must be increased.
  • Glukeosis. The cause of the disease is the fungus Microsporidia, which damages the eyes, internal organs and gills. In this case, infected fish swim on the side, and their body is covered with bloody spots. If the organs of sight are affected, a puffy eye is present. This disease, unfortunately, is incurable. Infected individuals and plants are exterminated, and the soil and equipment are disinfected.
  • Fin rot. Called wand Pseudomonas. Most often it strikes fish with elongated veiform tails that have undergone supercooling. Along the edges, the fins become cloudy and turn a bluish tint. During the progression of the disease, the fins rot, right up to the tail falling off in young individuals. Then the skin, muscles and blood vessels are affected, resulting in death. For the treatment using baths with malachite greens, antipar or "Bytsillinom".
  • Dactylogyrosis. The cause of the disease is the Dactylogyrus fluke parasite, which affects the gills of fish. In sick individuals, appetite disappears, and the gills change color (becoming variegated or whitish). Infected fish stay on the surface, rub against stones and breathe actively. The fins in the gill area are glued together, covered with mucus and sometimes eroded. The treatment of dactylogyrosis is reduced to raising the temperature of the water in the aquarium and adding to it solutions of formalin, table salt or Bicillin.
  • Ringworm. It is called mold fungus that affects the internal organs, skin and gills. Often appears again, as a complication of other diseases. Infected fish appear thin white threads on the gills and skin, then the internal organs are affected, and death occurs. Therapy begins with the cure of the primary disease, and then increase the immunity and use baths with potassium permanganate, "Bitsillin" and salt.
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Water quality

The main parameters of the liquid in the aquarium are: hardness, content of harmful impurities (chlorine and others), purity and level of acidity.

Why Do Fish Die In The Aquarium Tank For Beginners

Tap water can only be used after it has settled for one to two days. Otherwise, pets may experience chlorine poisoning.

Too soft water provokes the onset of alkalosis, and a decrease in the level of acidity. acidosis.

Temperature conditions

Why do fish die in an aquarium? Perhaps the reason lies in the wrong temperature conditions. The most suitable water is 22-26 degrees. However, some inhabitants, such as labyrinth fish and discus, are 28–30 degrees, and gold. 18–23 degrees.

Why Do Fish Die In The Aquarium Tank For Beginners

Too cold water can cause a cold to animals, and too warm. oxygen starvation (since the higher the temperature, the lower the oxygen content in the water).


If the fish die in the aquarium, what happened, you need to find out very quickly. Perhaps the cause of their death is old age. After all, fish, like other living creatures, are allowed a certain period of time:

  • Carps This group includes guppies, swordtails, petsilia and molinesia. Representatives of this species live only three and a half years.
  • Labyrinth: Betta Fish, lyapiuses, gourami. four to five years.
  • Kharatsinovye: tetra, neon, piranha, minors. about seven years.
  • Carp: barbs, telescopes, danios, cardinal. from four to fifteen years.
  • Cichlics: parrots, discus, severum, apistogramma, cichloma. from four to fourteen years. Angelfish in the aquarium, which also belong to this group, live an average of ten years.

Why Do Fish Die In The Aquarium Tank For Beginners

  • Catfish: Tarakatum, catfish glass and speckled. from eight to ten years.
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Determining an aging individual is quite simple: it swims poorly, becomes lethargic, the fins thin. Dead fish immediately removed.

Lack of oxygen

The content of this necessary component in water depends on the temperature, the number of inhabitants, aeration and the presence of pathological films on the surface.

Lack of oxygen can lead to asphyxiation (suffocation) of the fish. In this case, their gills open wide, and respiratory movements become more and more intense. The animal floats on the surface, greedily swallowing the air. After some time the fish dies with open mouth and wide open gills. If such symptoms are found, it will be necessary to find out and eliminate the cause of asphyxiation: spread the inhabitants, lower the water temperature, remove the film, clean the aquarium and change the water, purchase special equipment to enrich the water with oxygen.

With an excess of oxygen, gas embolism may occur.


If the fish die in the aquarium, what to do?

  1. Remove dead individual.
  2. Watch the rest of the pets (for changes in behavior, coloring, and so on).
  3. Check equipment (aquarium for beginners should have: oxygen supply, filter, thermometer, and so on).
  4. Check the condition of the water (determine temperature, acidity, hardness).
  5. In the presence of pollution. change the water, clean the soil and equipment if necessary.
  6. Adjust the light in the aquarium.
  7. Set aside the diseased or spread the fish when overpopulated.

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