Betta fish diseases

Betta ( siamese fighting fish ) fish are peculiar pets. Their tropical origins pose a problem for aquarists when looking after them. Monitor the condition of the pet to protect the bettas from ailments and emerging diseases.

Symptoms of the diseases are associated with a deterioration in appearance, impaired visual, olfactory functions, problems with the gastrointestinal tract, impaired motor functions, and the respiratory system.

Frequent problems


  • If all the inhabitants have symptoms at the same time, then the problem is usually in the environment: poor-quality water, lack of oxygen in the water, low temperature, nitrates.
  • If the problem affects only one species, and the other is not, then infectious diseases develop in the aquarium.
  • If only one inhabitant is ill, then there are problems with physical, mental illnesses, old age, injuries.

Conduct a thorough examination of the sick, check the water parameters and move the sick representatives to the quarantine tank.

Lies at the bottom

The most common symptom of betta disease is fish lying on the bottom.

The reasons:

  • Old age.
  • Cool water lowers the activity of tropical fish, which is why they fall into a lethargic state: they stop responding to food, stay in one place, the betta lies on the bottom, and breathes heavily. The low acceptable threshold for tropical inhabitants is considered to be a water temperature of 19-20 degrees.
  • If the pet is breathing heavily and lies at the bottom after transportation, moving to a different, unusual environment, a new aquarium, to other inhabitants, then this is completely normal. It’s just that the betta is under stress. After acclimatization, after a while, the betta will become active again.
  • But the symptom, when the inhabitant is breathing heavily while lying on the bottom, has more dangerous reasons. One of them is the chemical poisoning of the body. Check water performance with tests, move inhabitants to a favorable environment.


  • Dropsy is a bloated body.
  • Fin rot – white bloom on fins, their rotting.
  • Ichthyophthiriosis – white patches on the skin.
  • Oodinium is a red bloom and spots on the skin.
  • Gill fluke – gills are covered with mucus, parasites are visible.
  • Exophthalmia – bulging eyes.
  • Saprolegniasis is a white fluffy coating on the head, body, tail, similar to mold spores. Treatment with baths with salt and malachite green, antibiotics.

The course of treatment depends on the underlying disease. For prevention, they feed the betta fish 2 times a day in small portions, replace the water, disinfect new soil, and do not overpopulate the aquarium.


Betta does not eat

Lack of appetite isn’t always caused by illness. Safe reasons are the rejection of one type of food by the betta (more often this happens with dry food). In this case, try replacing your usual food with live food: brine shrimp, bloodworms, pieces of lean fish, squid. Another reason is that the feed particles are too large for him to swallow.

It is also normal that the betta fish does not eat after changing food or feeding the wrong type of food (for example, if you do not feed the predators with live food), moving in the aquarium. Many fish species do not feed during spawning and caring for fry.

If the betta takes food particles into his mouth but then spits it out, does not swallow, then perhaps something is stuck in his throat. Usually, it is a large lump of food, a particle of soil, a foreign object. Catch and examine the pet, preferably calling a veterinarian.

A sudden loss of appetite indicates possible constipation, especially if accompanied by a lack of excrement. But the adult inhabitants are able to cope with it themselves, it is enough not to feed the pets for a couple of days. But fry and pets with low immunity can be severely affected.

But usually, males do not eat and move little due to diseases. More often, a lack of appetite means infectious internal disorders of the body.

Common ailments in bettas with no appetite:

  • Ichthyophthirius is a disease caused by a species of ciliates and is detected when white spots appear on the pet’s skin.
  • Trichodina is a disease caused by parasitic infusoria. Malachite baths with high temperature and aeration help.
  • Mycobacteriosis is an infectious disease that affects males and humans. Antibiotic treatment.

Swollen belly

It is not always a symptom of the disease of the betta fish. The most common cause is overfeeding. Bettas are gluttonous, so they easily overeat. You need to feed them 3 times a day. If you feed live food, then the amount of food for one complimentary food is no more than 3 bloodworms per inhabitant. There is an indication of the amount of feeding with flakes and granules on the package.

One of the reasons for bloating in a betta is the spawning period. The sides and belly of females are rounded.

Bloating especially often precedes dropsy, when the internal fluid fills the whole body.

Another common reason is the settlement of tapeworms in the body, due to which the abdomen of the betta swells. For treatment, special agents are used, which the inhabitants swallow.

There is a high probability of an internal tumor. Most often, such inhabitants cannot be saved, especially in the late stages of the disease.

Vibriosis also causes abdominal distention. It is caused by vibrio bacteria. The disease is usually transmitted in salt aquariums, but bacteria are tenacious in freshwater tanks. It is treated with antibiotics.

Fins or tail stuck together

Fins and tail sticking together indicate improper housing or internal illness. Most often, fins sticking together indicate the onset of the disease, ichthyophthirius or fin rot. Treat them with antibiotics and baths with edible salt or malachite green.

Peeled off tail or fins

The causes of tail dissolution are divided into mechanical and disease-related causes. Mechanical damage is determined by observing life in the aquarium. Some inhabitants are not advised to keep with the owners of lush fins like bettas because they bite and pluck them. These are small species, not necessarily aggressive and territorial.

Overpopulation of the aquarium makes the inhabitants nervous. Some fighting fish even bite their own tail, perceiving it as an enemy.

Biting off the fins usually ends when a separate reservoir is allocated to the betta. So that the fighting fish is not bored, a mirror is installed in the aquarium, then the pet flaunts in front of the virtual enemy. Also, plant dense vegetation and sometimes rearrange the decor in the aquarium so that the pet can explore new places.

The tail and fins peel off with improper care of the bettas. The fish is sensitive to water parameters, temperature, chemical composition. The betta is able to live in unsuitable conditions and a small volume, but only for the period of transportation or movement.

Beautiful tail and fins indicate health, and when overpopulated, low temperatures, hard water, the tail will peel off.

Fin rot is another cause of fins and tail peeling.

Inflated gills

Swollen gills are usually not a serious symptom of an illness.

The reasons:

  • The betta flaunts in front of the rival, expecting the other to get cold feet and swim away. Thus, a hierarchy is formed in the flock with a strict definition of places for each inhabitant. Betta inflates its gills before a fight to appear larger and stronger.
  • The fighting fish inflates its gills during the breeding and spawning season to impress females with its size and bright colors. And the females are already choosing the most beautiful male for procreation.
  • Feeling unwell. This is manifested not only in swollen gills, but also in raised, ruffled scales, passivity, and lack of appetite. Usually, this condition indicates a bacterial or viral disease.

Contrary to popular belief, swelling of the gills in a betta does not mean a lack of air in the water and does not oblige to buy a compressor to enrich the water with oxygen. Bettas are labyrinth fish that are distinguished by their ability to breathe atmospheric air. Therefore, they do not need additional aerating devices, on the contrary, they will harm the fish, which does not tolerate water currents.

Jumps out of the water

The reasons:

  • Fighting and active pets constantly want to explore new territories and places, so they tend to leave the aquarium. This is more typical for species living in the upper layers of water in the reservoir.
  • Also, attempts to leave the aquarium are caused by fear and stress. Fish are frightened by sudden on/off switching of light, loud noise, impacts on the glass of containers with inhabitants, presence of large animals (cats) nearby and they accidentally jump out of the water in an attempt to hide.
  • Poorly chosen shape of the aquarium also contributes to attempts to escape from the water. Round shapes amplify external sounds and the fish are stressed and nervous.
  • The lack of space or overcrowding of the aquarium makes the fish jump out in search of a place to move and swim.
  • Dirty water worsens the condition of the fish, and they try to escape to a more favorable environment.
  • A malfunction of electrical equipment leads to a leakage of current, which is manifested by electric shocks of fish, and the human himself will not even feel them.
  • Large and carnivorous fish scare smaller inhabitants, and they tend to leave the dangerous territory.
  • Incorrect water change in the aquarium. It is bad to replace all the water at a time, the fish finds itself in a completely unusual environment with new chemical composition and experiences severe stress. Trying to return to the old water, the fish jumps out of the water.
  • Parasites irritate fish, interfering with their normal life. For treatment, use drugs against endo- and ectoparasites.

The bettas turned white

If the color of a bright betta fish suddenly began to change, discolor and some parts of the body turned white, then this is not a symptom of the disease, but a completely harmless mutation. In some breeding fish with this trait are discarded, but partial white coloration does not affect the health, behavior, or the ability to reproduce the fish. The whitewashing of the bettas color is just the result, the consequence of many crosses and breeding, in which the goal was to develop new colors by suppressing some genes. But in some representatives, these suppressed genes show up. One of them is the marble gene, which is responsible for the sudden change in the color of body parts to white.

A whitened betta does not need treatment, sometimes the marble gene is suppressed again and the original color of the fish returns.

Clouded or bulging eyes

Clouding or protrusion of one or both eyes in a betta fish is a consequence of improper care of the inhabitants of the aquarium. The water in such reservoirs is dirty, muddy, they have a high content of chemicals that appear during the decomposition of food residues and fish excrement.

First of all, check the quality of the water using tests for nitrates, nitrites, ammonia. Replace ¼ part of the water with clean and settled water. Do not forget about the temperature difference, which also lowers the fish’s immunity, which contributes to further protruding of the eyes.

Clouding of the eyes is also a consequence of incorrect indicators of acidity, rigidity. For males, the optimal conditions for keeping are considered acidity – 6–7.5 pH, hardness – 5–15 gH, water temperature – 27–31 degrees.

There is a high probability of the disease myrobacteriosis or, in other words, fish tuberculosis. All fish are carriers of this disease, but it affects the body only under poor conditions and low immunity of the betta. If the fish is sick, then it is treated with antibiotics.

Bulging of the eyes also indicates aeromonosis, pseudomonas, which have similar manifestations. Bulging of the eyes is the first symptom, so there is a chance of curing the fighting fish with drugs.


Large spots of different colors appear on the body of the fish: white, gray, red, black. This usually indicates a bacterial or fungal disease. But fish rubella or spring viremia is especially common with this symptom. It manifests itself at any time of the year. The incubation period for the development of the disease is a week. The disease spreads quickly from one fish to another. Red spots are localized near the head and fins in the front of the body. On multi-colored and brightly colored fish, the spots are easy to miss, they are especially clearly manifested on white representatives.

Talk to your veterinarian who will prescribe pills or antibiotics to cure your betta fish. But sick fish, especially if the spring viremia progressed strongly, is difficult to cure, the main task is to stop the spread of the disease. After healing the fish, the aquarium, the soil is treated and disinfected.

Spots – are a sign of spring viremia, Ichthyophthirius, and Oodinium. But in this case, the spots are small in size, and their colors are white or golden, depending on the disease.

Even sharply emerging spotting of fish indicates poisoning with nitrogenous compounds in the water. Do water tests and replace ¼ of the tank volume with fresh water.

Ruffled scales

Ruffled scales is one of the symptoms of a representative’s poor health, usually, the fish can no longer be helped because this means a long development of diseases. Tousled scales are closely related to dropsy disease. Usually sharpening scales means that soon the body of the fish will swell from the internal fluid, and this is a symptom of kidney failure. Fish do not live long without the proper functioning of the kidneys. Therefore, ruffled scales need to be recognized and addressed. To do this, during the daily inspection of fish, you need to inspect not only the fish on the sides. Open the lid of the aquarium and look at the inhabitants from above. This increases the chance of recognizing the ruffling of scales to dropsy.

The cause of ruffled scales is bacteria and viruses that have penetrated into the fish’s body and are already multiplying inside the body. For treatment, antibiotics and disinfection of the entire aquarium are used. Sick fish are removed from healthy ones. Healthy fish that do not yet show signs of illness are given baths with salt, malachite green.

A safer cause of ruffled scales is ectoparasites that settle between the scales and feed on fish skin and skin secretions. They are destroyed by baths with table salt.

Why bettas die

  • The most natural cause of death is old age.
  • Severe stress caused by abrupt changes in the chemical composition and parameters of the water. This includes a complete, rather than partial, replacement of water, in which the betta is in a completely new environment in terms of parameters. Too low temperatures also lead to death.
  • Toxins and poisons in water – nitrites, nitrates, nitrogenous bases, ammonium, ammonia. Poisoning with nitrogenous bases is determined by the persistent smell of decay coming from the water and cloudiness.
  • If you put an inhabitant in tap water, it can die from a gas embolism.
  • Unnoticed and untreated diseases such as Ichthyophthirius, dropsy, Oodinium, costia lead to death.

What to do if you find dead fish in the aquarium:

  • Remove the dead inhabitant from the tank.
  • Check other representatives for painful symptoms, all pets must be quarantined.
  • Examine a dead pet, check the condition of the abdomen, fins, eyes, gills, after putting on gloves, because many diseases of underwater inhabitants are transmitted to humans.
  • If inflammation, rotting of any parts of the body was found, then check other inhabitants for the same symptoms and select the appropriate treatment.
  • Check water parameters.

Diseases and treatment

Fin rot

Pseudomoniasis is especially painful in bettas, because their fluttering, lush fins become peeling, rotting. If untreated, it completely eats away the fin skin, leaving only fin rays.

Fin rot

Reasons: The bacteria that cause fin rot are constantly present in the aquarium and are not harmful if there is no reason for a sudden development. These include:

  • Contamination of soil by waste and food.
  • High population density of the reservoir.
  • Violation of the chemical characteristics of water or biobalance.
  • Infections with new inhabitants.
  • Poor water filtration.
  • Lack of cleaning the aquarium.

Symptoms: fading of the bright color of the betta, fins stick together, the skin puffs up and peels off, the cornea of ​​the eye is cloudy, ulcers form at the roots of the fins, holes appear, the skin of the fins decomposes, only rays remain.

Treatment: medicines to combat bacterial and fungal diseases. Baths with table salt, malachite green, and bicillin also help. Specialized preparations have been developed to combat fin rot.

Prevention: maintaining cleanliness and timely cleaning of the soil, the presence of a powerful filter.


A dangerous bacterial disease in fish, but it is also caused by parasites. Dropsy is characterized by swelling of certain parts of the body or the entire body. But dropsy is usually considered a symptom of more serious diseases. The most common: mycobacteriosis, aeromonosis, hexamita.

Fantastic video about dropsy in fish, excellent quality:

Dr Loh explains the causes of dropsy and does a full examination of a bloated Goldfish
The disease does not affect all representatives at the same time – in fish with strong immunity, dropsy may not develop at all. Young animals suffer more often. The first place that dropsy affects is the intestines because bacteria and parasites enter the digestive organs through the mouth. The excrement becomes unhealthy in color and becomes covered in mucus. The fish is not able to fully digest food, but sometimes it still continues to eat it. Other internal organs are gradually affected. When the disease reaches the kidneys, and they do not perform work, then a characteristic sign of dropsy appears – the body swells from the internal fluid, provoking bulging, raising the scales.

Reasons: bacteria, parasites, kidney damage, stress for a long time, sudden and frequent temperature changes, poor quality food, mainly from the meat of warm-blooded animals.

Symptoms: swelling of the abdomen, bulging, mucus in the excrement, white mucous pieces of intestine sticking out of the anus.

Treatment: drugs and feed, depending on the cause of the disease.

Prevention: maintaining a clean aquarium, maintaining immunity, a varied diet.

Bulging eyes (exophthalmia)

Aquarists consider exophthalmia or bulging eyes as a separate, isolated disease, and as one of the symptoms of more serious diseases. It is more often caused by the inhabitants parasitizing in the body, infection. It usually manifests itself with dropsy – the accumulation of fluid in the intestines of the fish.

During exophthalmia, fluid accumulates behind the eyeball and gradually enters the eye itself. One or both eyes can be affected.

How to Treat Popeye
Causes: bacterial diseases, infection, fungal diseases, an insufficient amount of vitamins in food due to monotonous diet, abnormal course of physiological processes, viruses, ocular trematodes. Poor water quality, chemical additives, nitrates, toxins contribute to the development of the disease.

Symptoms: cloudiness of the lining of the eyes, bulging of one or both eyes, possibly even falling out of the orbits. Appetite decreases, fish activity decreases, cowardice and photophobia are manifested.

Treatment: to establish the causes of the disease: infection, parasites, viruses, bacteria and get rid of the cause of the disease with drugs. If the cornea is clouded (which indicates poor quality water composition), replace part of the water every 2 days.

Prevention: Timely cleaning of the aquarium.


Ichthyobodosis or osteosis (the outdated name) is caused by a flagellate parasite. Especially often it affects young fish that are prepared for sale – because they live in cramped conditions. It is quickly transmitted to all fish of any species. Adult fish are less likely to get sick, but they tolerate Ichthyobodo and, upon contact, infect others. These parasites are hardy, it is quite difficult to recognize and destroy them, because they tolerate low and high temperatures and are indifferent to the acidity of the water.

It is difficult to save fish infected with costiosis.

Couldn’t find the video of betta fish with costia, but here is good example on how it looks on fish.

Identifying and Treating Costia/Protozoan Parasites on Goldfish
Reasons: caused by parasites when a diseased fish that has not undergone quarantine is moved in, feeding with infected and untreated live food, non-disinfected soil.

Symptoms: the betta is experiencing severe itching of the skin, so it begins to rub and itch against the walls of the aquarium, plant stems, stones. Motor functions are impaired, the fish does not swim smoothly, but makes sharp, angular movements. Often swims not head first, but sideways. Blue-gray spots of medium size appear on the skin. The fish feels suffocation and lack of oxygen due to mucus accumulating on the surface of the body, gills, and fins. Lack of appetite.

Treatment: immediately after the detection of costiosis, prepare a container for a salt bath. Place sick fish there 3 times for 10 minutes per day. Salt concentration: 1 teaspoon of edible salt per liter of pure water. They enhance the effect of salt with the help of a potassium permanganate crystal.

Prevention: Quarantine for purchased fish.


A common disease in aquarium fish. In another way, Columnaris is also called oral fungus, because the external manifestations of the disease are similar to a fungal infection.

Good video explaining how to fight off this disease, pitty i couldn’t find any video with betta fish.

How to: 4 Steps Columnaris Treatment Fish Bacterial Infection
Causes: the causative agent of the disease is bacteria that live in freshwater reservoirs. They are often found in tropical fish species, because bacteria require a high temperature, which is present in tropical fish, for successful reproduction. They are especially active in confined spaces, where bacteria are quickly transmitted by contact with fish. Therefore, a small aquarium or overcrowding, untidiness of the aquarist, and contamination of the aquarium with waste and food will create a favorable environment for the development of columnaris. Another reason is the lack of oxygen in the water, which often happens if the filter does not work well.

Symptoms: detachment, detachment from the outside world, the fish does not perceive the world around it. The betta spends a long time in one place (usually huddled in a shelter or vegetation), does not swim. On the head, lips, in the area of ​​the mouth, gills, fins, gray-white spots, similar to cotton wool, fluff is formed. If untreated, bacteria erode the skin and muscles in place of the white spots, and the gills decompose.

Treatment: helps to reduce water hardness and acidity. Salt baths and antibiotics help.

Prevention: avoid overpopulation of fish.

Oodinium (velvet disease)

Oodinium, or velvet disease, the causative agent is the oodinium parasite. The external manifestations of oodinium are similar to Ichthyophthirius, but the difference lies in the color of the neoplasms on the skin. With Ichthyophthirius, they are white, and with oodinium, yellowish.

Infection and disease progression passes quickly. If you look at the moment of the first manifestations of velvet disease, then the fish will be difficult to cure, sometimes even impossible.

Reasons: overcrowding, high water temperature, lack of cleanliness of the aquarium.


Symptoms: Small nodules that resemble golden dust or flour form on the body and fins. The behavior of fish differs: some swim nervously, rub against walls and plants due to itching of the skin, others are inactive, stay in one place in the shade for a long time. In bettas, long fins stick together due to mucus and hang in a lump. Later, the skin of the fins between the rays rots. Parasites increase the secretion of mucus, which causes a lack of air, suffocation.

Treatment: sick fish are transplanted into a separate tank with a temperature of 26 degrees. They are treated with a solution of malachite green, and then they are fed small amounts of live food. Then the next day, treat with copper sulfate and raise the temperature to 30 degrees. Process all inventory and aquarium.

Prevention: keeping the aquarium clean.


Ichthyophthirius is a fish disease that causes ichthyophthirius ciliates. In large reservoirs, where there is a constant change of water, the disease develops weakly, but in closed systems, especially in aquariums, ciliates quickly infect all inhabitants.

Aquarists often believe that these ciliates live in any water and the fish organism can easily cope with them. But this is not so – ichthyophthirius enter a new environment through the colonization of new fish, decor, and sterilization. More often, representatives with a light color become the carriers of ichthyophthirius, since they do not show the symptoms of parasites.


Reasons: lack of quarantine for newly purchased fish, lack of disinfection, untimely cleaning of the aquarium, pollution, overfeeding, high density of fish in the aquarium, low temperature.

Symptoms: white spots of ichthyophthirius appear on the body of a fighting fish, which outwardly resembles semolina granules. Lethargy, lack of appetite, shortness of breath, itchy skin.

Treatment: for the destruction of parasites on the surface of the skin of fish living in the water column, drugs that have a strong effect, but do not affect the fish, help. ichthyophthirius also do not like high temperatures, so 35 degrees will shorten the life cycle of parasites and kill them.

Prevention: all new fish are quarantined, the aquarium is kept clean.

Gill flukes

A fish that gets sick with gill flukes or monogenea, which were not found in time, dies from insufficient air or asphyxiation.

Reasons: relocation to the aquarium of new exotic fish species, which were recently caught from the wild and were not quarantined. Rarely is infection with untreated live food.

Symptoms: the skin and gills of the bettas are covered with thick mucus that interferes with breathing, the color fades, the body swells, the gills protrude to the sides. The swelling of the gills is also observed. The patient refuses food, spends all the time lying on the bottom. Rarely, the aquarist himself can see gill flukes when they reach large sizes and protrude from the gills due to lack of space.

Couldn’t find a good video on how gill flukes

Gill flukes
Treatment: to get rid of gill flukes, baths with formalin, potassium permanganate, very weak ammonia, Metrifonate, and Malathion are effective. Feed the fish rarely and in small portions. Place diseased fish in a separate container to prevent further spread of the disease.

Prevention: frozen food, not live food, keep the aquarium clean, change part of the water every week, monitor water parameters.

Prevention: Many causative agents of dangerous diseases are in contact with fish all the time, live in the same environment, and do not manifest themselves without reason. Therefore, the treatment of betta fish diseases will not be required if prevented through prevention.

Disease prevention:

  • Keeping the aquarium clean is considered the best preventive measure against all diseases. In a polluted tank, pathogenic bacteria and viruses actively multiply.
  • Knowledge of optimal conditions for keeping males. They have boundaries in care, outside of which they feel bad and get sick. This is especially true for the temperature of the water, to the readings of which the males are especially sensitive: sudden changes cause stress in the fish and reduce immunity.
  • The parameters of water, acidity, gases, hardness, chemical indicators strongly affect the well-being and health of fish. These parameters must be monitored by the aquarist to keep them within acceptable limits.
  • Quarantine is compulsory for all purchased fish. New inhabitants should not be allowed into the aquarium until the month-long quarantine has ended. And only after you are convinced of the health of the fish, it is launched to other inhabitants.
  • Disinfection of new decorative elements, soil, artificial plants is required.

Diseases of fighting fish are difficult to recognize without the experience and knowledge of a veterinarian, but according to the symptoms, even a novice aquarist is able to recognize the disease and help the pet in time. But it is better not to lead to diseases at all, maintaining the necessary balance and cleanliness in the aquarium.