Useful Tips

How to cure fin rot in a common aquarium


This disease has a bacterial origin and is very contagious. The main culprits of its development are the pathogenic bacteria Aeromonas punctata and Pseudomonas fluorescens.

Bacteria of the genus Aeromonas are anaerobic bacilli, that is, for their vital functions, both a small amount and a complete lack of oxygen are sufficient. Pseudomonas fluorescens aerobic species of organisms, so oxygen is needed for their development, but some strains can use nitrates instead of oxygen. Regardless of the genus, both bacteria settle both in fresh water and in brackish.

A common sign of infection is red spots on the body and fins of fish. The disease without treatment progresses very quickly and leads to the death of the inhabitants of the aquarium / pool. Therefore, it is important to notice the first signs of infection in time and prevent its spread.

It is difficult to cure young fish, the mortality rate among them from this disease is high. Adult individuals often recover, but their fins do not recover — they remain shortened with uneven edges, their rays with breaks and nodes. If the ulcers have passed onto the body, then most likely the individual will die.

Which fish get sick more often?

Most often aquarium fish are subject to fin rot. In the high-risk zone, fish with long and veil fins:

  • scalars,
  • guppies
  • cockerels
  • veil-tails ("goldfish"), etc.

Pond fish in cage farms can also suffer from the bacteria in question, but for them this disease is less common. According to our observations, it is precisely young salmon that are susceptible to this disease. For them, adult sick individuals and their corpses are considered a source of infection.

Causes of the disease

The presence of pathogenic bacteria in the aquarium or pool is considered normal if their number does not exceed the norms and the conditions for keeping fish are not violated. The immunity of fish copes with bacteria living in a reservoir, which does not provide an opportunity for the development of their disease. But everything changes when the number of microorganisms begins to grow or the fish immune system weakens due to poor care.

Factors affecting the development of the disease:

  • Violation of the temperature regime. Each type of fish feels comfortable at a certain water temperature. The increased or decreased temperature of the environment in which the fish live can lead to shock in aquatic inhabitants and, consequently, a decrease in immunity.
  • Stress in fish due to a sharp change in water parameters. If you replace a lot of old water with new water in an aquarium or start a fish in a reservoir without preliminary preparation, animals will experience severe stress, which can lead to a decrease in the body's ability to withstand diseases.
  • Bad water parameters. A rare water change, rotting aquatic plants, water pollution, inappropriate pH values ​​of the aquatic environment - all this is the reason for the deterioration of the well-being of fish and increase their susceptibility to pathogenic bacteria.
  • Aggressiveness of fish. Barbuses, scalars, cichlids, gourami, etc. can inflict wounds on civilians and on each other when overpopulated. Carps are very voracious, and can eat smaller fish or injure young animals when trying to get more food. Open damaged areas and become sources of infection.
  • Nutrition Intensity and Feed Quality. Feeding the inhabitants with “live” food is preferred, but vitamin-containing as well as plant-based food are also needed, so you need to alternate all types of food in order to provide the fish with a varied and complete diet. Improper feeding and overfeeding contribute to a decrease in immunity.
  • Infected New Residents. When replenishing the number of fish, beginners must be quarantined or special additives (disinfecting + enhancing immunity) must be preventively added to the general water.

If a disease occurs in at least one individual, it is necessary to treat all the inhabitants who shared one reservoir with it. In order not to start the disease, regularly inspect your aquatic pets. The first signs are a bluish-white opacification of the edges of the fins, which was not previously observed. With the progression of the disease, the ends of the fins die off, then they are completely shortened or split into rays. Aquarists describe this disease as follows: “The fish seem to have“ decayed ”edges of the fins and seem to have a tail“ eaten up ”by someone, or“ The fish’s tail fin seems to have been torn to pieces and cracked in some places. ”

The presence of a combination of the following symptoms indicates an advanced stage of the disease:

  • red spots on the bases of the fins,
  • the irrigation of scales and its loss,
  • possibly ocular enlargement, abdominal enlargement,
  • fins are destroyed, erosion is formed in their place (the risk of infection entering the blood is high, then the fish die).

In the acute course of the disease, the fish dies en masse, in the chronic course - it is possible to save the fish if adequate and timely treatment is provided. The disease should not be confused with the usual fin injury, mycobacteriosis or ichthyophonosis. About what other fish diseases exist and what their symptoms can be found here.

At the initial stage, a regular water change of 30% of the total volume (every week) helps to cope with the disease, defended and heated to the maximum temperature values ​​that are considered optimal for spawning of your particular fish species. When replacing water, the soil siphon, wash the aquarium filter, get rid of rotten plants. If this does not help, then more radical means are used, various substances and drugs are used.


In a general aquarium or in separate bathtubs where a sick individual is placed, one of the following antibiotics is added:

  • Bicillin-5 in the calculation of 5000 units / l of water. The necessary amount of antibiotic is dissolved in the bath, and “patients” are released there. The procedure lasts 30 minutes. Treatment is carried out for 6 days.
  • Tetracycline (erythromycin is also suitable) at a dosage of 70-150 mg / l. Contribute to the general aquarium once a week for 2 months.

Antibiotics can be combined with antibacterial agents, such as streptocide. It is dissolved in a small separate container at the rate of 1.5 per 10 liters of water, and the solution is poured into the total capacity (i.e. if you have a 100 liter aquarium, then dissolve 15 g of streptocide in a jar and pour it into the aquarium).

Antibiotics should be added to the aquarium only as a last resort! Along with pathogenic organisms, they also kill beneficial bacteria, and this leads to a failure of biological balance in the aquarium, which in itself is not good for fish or other animals. Also note that some types of medicine are lethal to snails.

Other methods

In veterinary clinics you can purchase specialized tools for the treatment of fin rot: Sera Baktopur, TetraMedica General Tonic, Aquarium Pharmaceuticals T.C. Capsules etc. When using drugs, strictly adhere to the recommendations in the instructions.

During treatment in a general aquarium, decor from plastic and ceramics is removed from it, enhance air aeration and reduce the amount of live nutrition. Each breed requires an individual approach. So, it is better to treat a scalar without depositing in separate baths, because with frequent transplants, the already fragile health of the fish can worsen. A rooster is recommended to be treated in quarantine.

The breeder of aquarium fish in his video shares how he treats his wards for fin rot:

How to treat fin rot?

If the aquarist has started treating the infection at an early stage, then no problems should arise. First, you have to make a 30 percent change of water to fresh. Next, you need to increase the temperature of the water in the aquarium by the maximum possible value for your fish. This is a very important step, because not all fish can survive the temperature increase. If there are such fish in your aquarium, then fin rot rot patients are best treated in a special aquarium. If the above actions did not improve the condition of the infected fish, then it is time to proceed to drug treatment.

The methods of drug treatment are as follows:

  • Very well proven chloramphenicol. For 20 liters of water should be one tablet. To begin, grind the medicine into powder, pour it into a small container with water and dissolve it there. Then the resulting mixture was poured into aquas. Since chloramphenicol is poorly soluble, you will have to be patient. Then every 3 days you replace in the aquarium about 30% of the water with fresh water and fill in the next portion of the treatment solution. This procedure should be repeated until your fish feel better,
  • If you are treating sick fish in a common aquarium, then try streptocide. The proportion is as follows: for every 10 liters of water 1.5 grams of streptocide are needed. As with chloramphenicol, the medicine must be dissolved in a small container, and then the resulting mixture is added to the aquarium. Unfortunately, streptocid is also poorly soluble in water. Fin rot can be treated both in a general aquarium and in a separate tank. Take a tablet of streptocide and dissolve it in a 6-liter vessel. The temperature of the treatment mixture should be 28 degrees. Keep the sick fish in this container for half an hour and then send it to a common aquarium,
  • Another good drug that copes with fin rot treatment is bicillin-5. As a rule, bottles of 1,500,000 units are available. To treat the fish you will have to use up only 1/6 of the bottle, dissolving in 10 liters of water. The therapeutic mixture is poured into the bath, where sick fish are transplanted for half an hour. For the treatment of rot you will have to repeat this procedure for six days. In 6 days you’ll just use up the whole bottle of medicine,
  • Another medicine with which you can cure fin rot is Biseptol-480. It can be bought at the pharmacy. Since the drug is sold in tablets, you will have to grind it into powder. 5 liters of water should account for 1/8 tablet. Biseptol is treated for a week and for each procedure you need to prepare a new solution. A prerequisite is that the fish must always be in the medicinal mixture and aeration must be provided in it,
  • You will probably be surprised, but fin rot can be cured with salt. Take 3 teaspoons of table salt and dissolve them in a five-liter container with water. Then put in a therapeutic mixture of sick fish. Only you must take into account that this concentration is not suitable for all fish, because all fish react differently to salt water. While fish are treated in a separate container, the aquarium and decorations with equipment are sanitized and boiled. Aquarium plants must be treated in a solution of bicillin-5.


To reduce the risk of a disease, especially if you have fish breeds with beautiful long fins, follow a few rules:

  • Change 30% of the water to a new one weekly while cleaning the bottom of the aquarium. Remember, adding water is not the same as replacing it!
  • Feed your fish high-quality food, and do not overfeed.
  • When buying new inhabitants, be sure to quarantine them for 10 days.
  • Separate fish separately if in doubt about their health.
  • Do not use other people's equipment and uncontaminated soil.
  • Observe optimal fish keeping conditions.
  • Add preventative medication to the aquarium water. Most often, basic purple K or malachite green (sold in veterinary pharmacies) is used for this purpose, however, when using these products, care should be taken and the prescribed dosage should be observed so as not to harm the fish.

So, fin rot is a dangerous and highly infectious disease. But with timely treatment, you can not only restore the fins to the fish, but also save the lives of most pets.

Preventive actions

Those fish that have a weaker immune system are most susceptible to the disease. Poor conditions of detention can also be attributed to negative factors. It is possible that the reasons can be combined. Suppose a fish damaged a fin in an aquarium, and water in a jar of poor quality. But do not think that due to the banal damage to the fin, the fish will necessarily get rot. To reduce the likelihood of fish becoming infected with this infectious disease, you must properly feed your fish and provide them with good conditions.

Fin rot treatment preparations

  • SeraBaktopur,
  • AQUAYER AquaBactol,
  • TetraMedica General Tonic,
  • Chloramine solution (consistency - 0.5%),
  • Hydrogen peroxide solution (consistency - 3%),
  • Malachite green,
  • Streptocide
  • The main purple K,
  • Bicillin-5,
  • Biomycin,
  • Levomycetinum in tablets.

Here is another interesting video that I could find on this disease, I hope you enjoy it and you get useful information from it.


It is important to diagnose fin rot in the early stages of its manifestation and to treat it in a timely manner. What is noteworthy, adults after simple manipulations usually easily recover, while juveniles die without exception.

There are many reasons for this phenomenon, one of which is the weaker, undeveloped immune system of fry.

Fin rot treatment

The initial stage of treatment is to test and improve the internal environment of the aquarium. This includes a whole range of activities and is carried out sequentially and in its entirety.

First need

  • clean the filters
  • remove rotten plants from the aquarium, if any.
  • boil the soil, net, decor for 15-20 minutes before returning it back.

The next step is the replacement of water. The volume of the new fluid should be approximately 30%.

Since the disease has a bacterial etiology, it must be remembered that too high a temperature of the water can contribute to the development of bacteria, thereby exacerbating the course of the disease. The optimal temperature in the treatment of fin rot is 24-25ºС.

Let us consider in more detail, with the help of which medicines it is necessary to carry out the procedure and how long to treat the fish.

  • Adding chloramphenicol to the general aquarium. It is necessary to dissolve 1 tablet in 20 liters of water and every 3 days to change 30% of the total volume of water per drug solution until complete recovery.
  • Salt baths (not suitable for cockroaches and some other species, prior consultation with a specialist is necessary). Dissolve 1 tablespoon of salt in 10 liters of water and run the sick fish into the solution for 30 minutes.
    If the causative agent of the disease is the bacteria Aeromonas hydrophila and Pseudomonas fluorescens, then salt treatment will not bring any results, since these species are resistant to high salt content in water.
  • Biomycin treatment. 1.5 g per 100 liters of water. The drug is introduced into the general aquarium once a week. The course of treatment is long - 2-3 months.
  • Baths with potassium permanganate. 1 g per 20 liters of water. In this case, you must first dilute potassium permanganate in a separate container, then pour half into the total volume of water, start the fish, wait 5 minutes and add the remaining liquid. Application time - no more than 10 minutes, morning and evening.
  • There are a number of special antibacterial drugs that can be purchased at a veterinary pharmacy after consulting with your pharmacist or veterinarian.
  • Streptocide treatment. 1.5 g per 10 liters of water. First dissolve, then add to the aquarium. Or apply in the form of baths at a dosage of 1 tablet in 6 liters of water. They should place a sick fish for 30 minutes.
  • Baths with formalin. 1 ml per 6 liters of water. Acceptance time - 15 minutes. To test tolerance, you should first place the fish in the solution for a shorter time, and if it becomes ill, stop the procedure and transfer the patient to clean water.

At the end of treatment, the process of regeneration of the fins will gradually begin, which will mean the success of the procedures. If this does not happen, a different treatment method should be used.

If treatment is started in a timely manner, then all the inhabitants of the aquarium will be saved without high costs and complex manipulations.

One response

We cured our cockerel with chloramphenicol. Studies were conducted (honestly, I don’t remember which site I saw) you need to dilute 20 mg of chloramphenicol per 1 liter and make baths (they did not replace the water in the aquarium, namely, they started the cockerel for 2 hours in a jar of solution). 500 mg in one tablet, but chloramphenicol does not completely dissolve, so I think 1 tablet can be diluted in 20 liters of water. You can not use drops of chloramphenicol, as it contains boric acid, and this is death for fish! Generally. We bought pure chloramphenicol in the pharmacy, not pills, but powder (not in every pharmacy, only those that can produce drugs themselves) and began to dilute it 20 mg per 1 liter, start the fish there for 2 hours, and then back to the aquarium At the same time, every day we replaced 30% of the water with clean water (we took water from a well, if from a tap, then water should be defended for at least 3 days). And so 10 days. In this case, we pulled out all the stones and algae from the aquarium, washed it, and put it back only after 10 days of treatment. We did not pour chloramphenicol into the aquarium. Через 10 дней хвост начал заново отрастать и рыбка начала хорошо кушать!

Какие рыбы могут заболевать

Чаще всего гниль плавников развивается у барбусов, голубых неонов, золотых рыбок, лабиринтовых и живородок. В особенности опасна эта болезнь для молодняка. Ткани плавников и хвоста у таких рыбок еще очень нежные и «растворяются» из-за гнили практически моментально. Adult individuals pick up rot much less often, and the disease itself passes easier.

But, of course, the most dangerous rot is for fish with luxurious tails and fins. This mainly concerns such beauties as veil-tails. The onset of the disease can completely reduce the decorative qualities of these aquarium inhabitants to nothing. Therefore, the methods of its treatment and prevention will be most useful for the owners of this popular variety of goldfish to learn.

The main reasons for the development

Causes fin rot a special kind of bacteria - Pseudomonas fluorescens. In this case, the main causes of infection are:

  • poor quality water
  • improper feeding
  • aggression of other fish,
  • stress and infections (bacterial).

What drugs can be used

If a disease such as fin rot is detected in goldfish, treatment can be carried out using either purchased means or ordinary home ones, always at hand. The same goes for other species of aquarium inhabitants. Most often from this disease they use:

Sometimes owners of aquariums also use other drugs to identify diseases such as fin rot in goldfish. Treatment with methylene blue, for example, can give a certain result. However, this tool is not too strong and does not always help. Of the special preparations purchased, TetraMedica General Tonic and SeraBaktopur are usually used. These are very effective means. You can also try to treat rot with bicillin-5 or malachite green (not to be confused with diamond).

How to treat

Fin rot treatment is best done in a common aquarium. This can prevent the re-development of the disease or infection of other fish. The fact is that the bacteria causing rot rot enter the aquarium usually with river soil, food or plants taken from open water bodies. Thus, disinfection carried out directly on the spot will make it possible to get rid of the very cause of the disease.

In a separate vessel, the rot of the fins is treated only if there are some healthy fish in the aquarium that cannot tolerate the drug chosen for this purpose. Before starting the procedures, it is mandatory to replace water in the aquarium by 30-50%. You will also need to raise the temperature to the maximum allowable for this particular species of fish. If there are healthy representatives of the fauna in the aquarium that do not tolerate warm water, the diseased person with rot should still be treated in a separate vessel. In this case, the aquarium itself will subsequently need to be disinfected separately. To do this, remove all fish and snails from it, and then remove and thoroughly wash the soil and plants in a solution of bicillin-5. Plastic and ceramic disinfection decorations can simply be boiled.

The benefits and principle of action of peroxide

Fin rot in goldfish, labyrinths, livestock, etc. with the help of this tool can be cured quite quickly. The principle of peroxide is simple. Firstly, it saturates water with oxygen (which is good for fish in any case), and secondly, it oxidizes well the organics that make up the components of the cells of the bacterium that causes the disease.

Fin rot: treatment in a common aquarium with hydrogen peroxide

Apply h2O2Of course, it should be right. To treat fish from fin rot, a 3% solution of this substance is used. It is such peroxide that is sold in pharmacies in liquid form. If necessary, you can make a 3% solution from tablets. On a glass of water they will need 6 pcs. For the treatment of rot rot, 2-2.5 ml of the product per 10 liters of water are needed.

Of course, pouring a pharmacy or tablet solution prepared directly from a glass or bottle into an aquarium is not possible. After all, at the same time, you can accidentally get a jet on some fish and burn it. The same goes for plants. It is better to dilute the required amount of peroxide with water in a half-liter jar and carefully pour everything into the filter stream. Add H2O2 in the treatment of a disease such as rot of fins, the aquarium should be 1-2 times a day until the fish recover (7-14 days).

Since after using this product a lot of dead organics appears in the aquarium, at least 30% of the water should be changed daily during treatment. Otherwise, rotting residues can cause fish poisoning.

Peroxide is a cheap and quite effective remedy. When it enters the aquarium, an active reaction begins to occur. In this case, the substance decomposes into two harmless components - oxygen and water. But despite this, it is worth using peroxide only if the rot of the fins of the veils, barbs, viviparous, etc. in severe form is detected. At the initial stage of fish, it is better to treat with some more sparing purchased means. In any case, you need to add peroxide to the aquarium in an amount of not more than 2.5 ml per 10 liters of water. Otherwise, aquatic plants will be damaged. In particular, they do not like wallisneria peroxide, all kinds of mosses, camboba and hornwort. Adding 4 ml of this substance per 10 l to the aquarium will be dangerous even for the fish themselves. Fortunately, peroxide has no special effect on the bacteria of the biofilter.

How to treat rot with salt

This is another cheap and quite effective tool. A very good solution may be its use in identifying a disease such as fin rot in goldfish. Salt treatment to some other types of fish, unfortunately, is contraindicated. They do not tolerate its presence in water, for example, barbs and all labyrinths. Livestock, on the contrary, love her very much. Therefore, salt can be used to treat fin rot not only with veil tails and ordinary goldfish, but also with guppies, swordsmen and malls. The correct dosage in this case will be 1 tbsp / liter per 10 liters.

Treatment with streptocide and chloramphenicol

Both of these funds can be purchased at a pharmacy without a prescription and at a low cost. Chloramphenicol may have a negative effect on the microflora of biofilters. Therefore, for treatment in a general aquarium, it should be used as carefully as possible. The required dose of chloramphenicol is 500 mg per 10 liters. This remedy has a beneficial effect on fish fins within 48 hours. Then you will need to replace as much water as possible. Next, 500 mg of the drug should be added back to the aquarium (and so on up to four times).

Antibiotics are generally a very good remedy for a disease such as fin rot in goldfish. Treatment with streptocide, for example, can also be carried out both in a separate tank and in a common aquarium. Of course, this drug can be a good solution for any other species of fish. The required dose of streptocide in the detection of rot is 10-20 g per 10 liters. This amount of drug must be added to the aquarium every 8 days for a month. And of course, in this case, it is also worth more often to do a water change in the aquarium.

How to prevent the development of the disease

Usually only fish with weakened immunity are infected with fin rot. Therefore, the prevention of Pseudomonas fluorescens infection consists primarily in good care for the aquarium inhabitants. To prevent infection, you must also disinfect the new soil before laying it. Do not plant in the aquarium and no plants taken from ponds, lakes or rivers. To provoke the development of fin rot in fish, among other things, too low a water temperature can. Therefore, it is necessary to monitor the correctness of the thermostat.