Betta Inflamed Gills – Symptoms, Treatment & Prevention

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Many first-time betta owners find themselves at a loss when their betta suffers from inflamed gills. Why are their fish’s gills swollen? And why are they gasping for air? These symptoms can be alarming for any hobbyist, as breathing difficulties in fish usually hint at a life-threatening condition.

Fortunately, betta gills can get inflamed for a variety of reasons. Many of these reasons can be easily prevented and remedied. If you are a first-time betta owner, read on to learn about how to spot, prevent, and treat inflamed gills in betta fish!

How Do Gills Work For Betta Fish?

Abstract close up art movement of Betta fish,Siamese fighting fish isolated on black background.Fine art design concept.

Gills are an essential component of your betta’s respiratory system. They consist of a network of blood vessels, through which oxygen and carbon dioxide can be exchanged. Oxygen is absorbed into the body via the gills, while carbon dioxide is expelled as a waste product.

The gills are flanked by a pair of flaps known as the operculum. As water is drawn into the gills through the fish’s mouth, the operculum closes to keep the water in the gills while oxygen absorption takes place. After this process is complete, the operculum opens to release water and carbon dioxide into the surroundings. This is how most fish breathe.

Bettas are unique because they have a labyrinth organ right above their gills. Think of the labyrinth organ as a backup breathing system for bettas in oxygen-poor waters. Because wild bettas live in shallow bodies of water, being able to inhale oxygen from the atmosphere with their labyrinth organs can be crucial to their survival.

What Do Inflamed Gills Look Like?

Inflamed gills typically look dark red, and have a swollen appearance. Gills become inflamed as part of your betta’s bodily response against external attacks.

Blood vessels near the affected area dilate to bring white blood cells closer to the injured tissue, allowing immune responses to take place. As a result, this causes inflamed gills to look dark red and swollen.

Early detection results in a significantly improved prognosis. If you spot any of the following symptoms of inflamed gills, be sure to act fast and take immediate action!

Signs And Symptoms Of Inflamed Gills In Betta Fish

Spotting the signs and symptoms of inflamed gills in betta can improve your odds of treating its underlying cause. Because early symptoms can be subtle, we’ve created a table to help you delineate between healthy gills and inflamed gills:

Healthy Gills

Inflamed Gills

Opens and closes entirely

Does not close completely

Light shade of red – almost pinkish

Dark red – appears on the verge of bleeding

Flat surface

Swollen surface

Breathes normally

Gasping for air – bettas might do so on the surface of the water as they have labyrinth organs

Opens and closes at a consistent, steady pace

Opens and closes rapidly to compensate for lack of oxygen

Healthy Gills

Opens and closes entirely

Inflamed Gills

Does not close completely

Healthy Gills

Light shade of red – almost pinkish

Inflamed Gills

Dark red – appears on the verge of bleeding

Healthy Gills

Flat surface

Inflamed Gills

Swollen surface

Healthy Gills

Breathes normally

Inflamed Gills

Gasping for air – bettas might do so on the surface of the water as they have labyrinth organs

Healthy Gills

Opens and closes at a consistent, steady pace

Inflamed Gills

Opens and closes rapidly to compensate for lack of oxygen

Inflamed Gills Look Dark Red

Healthy gills are a bright shade of light red, as they are filled with blood vessels running close to the surface. This allows oxygen to diffuse from the water into the fish’s bloodstream.

Meanwhile, inflamed gills are dark red in color and can look like they are on the verge of bleeding. Blood vessels in the gill dilate to bring blood closer to the skin’s surface when the surrounding tissues are injured, causing inflamed gills to take on a deeper shade of red.

Gills Appear Swollen

Inflamed gills always look swollen. The science behind it is simple. Inflammation is often caused by injuries or infections. When gill tissues are injured, the body does its utmost to carry more white blood cells to the region. This is because white blood cells act as the body’s natural defense system.

The process of carrying more white blood cells to the region causes blood vessels to dilate. These dilated blood vessels take up more space, causing gills to appear swollen.

Gills Are Unable To Close Completely 

When blood vessels in the gills dilate, they take up more space and also the surrounding tissues to swell. This swelling prevents the operculum (gill flaps) from laying completely flat when they are supposed to close.

This is an issue because closed operculum traps oxygen-rich water in the gills, allowing oxygen transfer to take place. When gills don’t close completely, oxygen-rich water escapes the gills before the oxygen has been fully absorbed into the bloodstream.

Note: There is a difference between bettas that are flaring their gills, vs bettas that are unable to close their gills due to inflammation. The former is an attempt to warn off predators, while the latter can lead to complications that prove fatal.

Gill Flaps Open And Close Rapidly

Fish with inflamed gills breathe more rapidly as there is less oxygen in their body. When observed, this can look like gill flaps that are opening and closing at a quicker rate.

This occurs because gill inflammation prevents oxygen transfer from taking place efficiently. When the fish detects a lack of oxygen in its body, it breathes more rapidly in an attempt to make up for any deficiencies.

Unfortunately, this elevated rate of breathing is not sustainable and can result in death if not treated. Therefore, you should take immediate action when you notice that your betta’s gills don’t close completely.

Bettas Will Gasp For Air

Fighting fish (Betta splendens) Fish with a beautiful array of colorful beauty.

Bettas are capable of breathing air from the surface of the water, so a betta with inflamed gills can often be seen gasping for air to make up for oxygen deficiencies.

Wild bettas live in areas with low amounts of dissolved oxygen. As a result, bettas have evolved to rely upon their labyrinth organs to inhale oxygen from the atmosphere when they are struggling to breathe. 

Similarly, bettas with inflamed gills gasp for air on the surface of the water as this is what they are accustomed to doing. Unfortunately, this is not a sustainable survival strategy in the long run.

Treating Common Causes Of Inflamed Gills 

Inflamed gills are usually a sign that your betta suffers from an underlying illness or infection. When you notice symptoms of inflamed gills in your fish, you should aim to identify the specific cause of inflammation, which will in turn allow you to provide your fish with the appropriate course of treatment.

Here’s a guide to identifying and treating the common causes of inflamed gills!

Gill Flukes 

Gill flukes, otherwise known as the Dactylogyrus parasite, are one of the leading causes of inflamed gills in bettas. They act by lodging themselves in your fish’s gills, before laying eggs and multiplying. 

A telltale sign of gill flukes is the presence of a worm-like parasite projecting from the gills of your fish. In response to an infection by gill flukes, the gill produces more mucus, which has a suffocating effect. This causes your betta to open and close its gills more rapidly, and gasp for air on the surface of the water. 

Gill flukes can usually be found in small, harmless quantities in your fish’s habitat. However, a poorly maintained tank causes these parasites to be present in large numbers, which leads to the complications mentioned above.


Place your sick betta in a hospital tank, and treat it with anti-fluke medication. You can obtain specially-formulated medicine from your vet, or opt for over-the-counter alternatives such as API General Cure.

You will have to perform two rounds of treatment if the Dactylogyrus has successfully deposited eggs on the gills of your betta. The first treatment gets rid of the first generation of parasites, while the second treatment kills the gill flukes that emerge after the eggs hatch.

Bacterial Gill Disease

Bacterial Gill Disease is caused by a type of bacteria known as myxobacteria (flavobacterium branchiophilum), and can cause inflamed gills. It is often associated with the overcrowded conditions found in fish farms. Overcrowding precipitates a decline in water quality, which in turn allows bacteria to thrive and grow in large quantities. 

When a large number of myxobacteria make their way onto the gills of fish, Bacterial Gill Disease occurs. This causes gills to appear dark red and swollen. Other signs include the presence of white or gray spots on the gills of your fish.

As the disease progresses, your fish’s gills may start clubbing or fusing together. This reduces the amount of surface area available in the gills for oxygen transfer to take place. Bacterial Gill Disease can be fatal if not treated appropriately.


betta fish, siamese fighting fish in aquarium

The old adage “prevention is better than cure” rings true in this instance. Bacterial Gill Disease is difficult to cure, but can be easily prevented by maintaining optimum rearing densities and keeping water conditions as clean as possible. 

Infected fish should be placed in a hospital tank to prevent cross-infections. According to the Michigan Department of Natural Resources, Chloramine-T is typically an effective cure, though it is not approved for general use due to its carcinogenic properties. Some hobbyists have also had success with using potassium permanganate in a 1:10 ratio for 30 seconds.

Gill Hyperplasia (Scarring)

Gill hyperplasia is one of the leading causes of inflamed gills in betta fish. It occurs when gill tissues attempt to heal from an injury or infection, but end up growing too many cells as part of the process. This causes the gills to enlarge and take on a swollen appearance. 

The best way to prevent gill hyperplasia is to minimize the risk of infections and injuries. Keep your tank clean, and make sure to remove tank decor that can injure your betta’s gills – particularly ones with sharp edges. If your betta is housed with tankmates, make sure that gill injuries aren’t occurring as a result of fights or gill-nipping. 


Once your fish has developed gill hyperplasia, there are a few things you can do to speed up the recovery process. First of all, you should perform a 50% water change to establish optimum tank parameters. This will eliminate stressors that may inhibit recovery.

Treating your water with a soothing water conditioner such as API Stress Coat can create a comfortable tank environment for your fish as the gill hyperplasia runs its course. It also fights off pathogens and promotes wound healing, allowing your betta to recover from gill hyperplasia without risking secondary infections and illnesses.

Physical Injuries

Inflamed gills can sometimes be the result of physical injuries. Gills are sensitive organs that can be easily injured by accidental contact with your hands, or with a rough-textured net. For that reason, it is important to be extra careful when handling your bettas.

Physical injuries can also be caused by aggressive tankmates, or by tank decor with sharp edges. Remove the initial source of the injury before you proceed with treatment.


Inflammation and discoloration will highlight the contact point where the injury occurred. Swelling may occur, which will prevent the operculum from closing completely and affect your betta’s breathing. However, most cases of minor physical injuries recover on their own.

Severe injuries may develop into complications such as gill hyperplasia. However, rapid treatment with aquarium salt can go a long way in preventing severe infections. Adding aquarium salt to your tank also improves gill function and replenishes body salts lost from stress-induced osmoregulatory dysfunction.

Ammonia Poisoning

Ammonia poisoning can cause significant gill damage in your bettas, resulting in gills that appear red and inflamed. It occurs when ammonia levels in your betta tank rise to unhealthy levels, creating a pH imbalance that is toxic and often fatal to your bettas.

Ideally, tanks should contain zero ammonia. However, bettas can stay relatively healthy as long as ammonia levels are kept below 0.5ppm (parts per million) in their tank. Once ammonia levels rise beyond this level, ammonia poisoning occurs. The condition can unfold suddenly, or over a period of days.

Unfortunately, ammonia poisoning can be fatal if not caught and treated early. It begins by attacking your fish’s gills and causing lethargy, before finally progressing to cause internal bleeding and organ damage. Here’s what you should do if you suspect that your betta has ammonia poisoning:


Fundamentally speaking, ammonia poisoning has to do with a severe pH imbalance. Therefore, the most immediate thing you should do is lower the pH level of your tank. You can do so by performing a partial water change. In mild cases, this will usually provide immediate relief to your bettas.

More severe cases of ammonia poisoning will require treatment with a chemical pH control product. This will neutralize the ammonia in the tank and restore safe ammonia levels. You should also restrict feedings for a few days. This will prevent your fish from producing excess waste.

With prompt and vigilant care, ammonia poisoning can be treated effectively. However, it is best to keep your tank clean from the get-go, as this will ensure that your bettas stay healthy.

How To Prevent Inflamed Gills

Inflamed gills are much easier to prevent than they are to treat. Here are some of our top tips for how you can prevent inflamed gills in betta fish!

Betta-Friendly Tank Decor

Ourple betta fish in aquarium.

Bettas are curious, active fish that like to explore their surroundings. You should expect them to swim around and explore every crevice of their home, which is why betta-friendly tank decor is extremely important to prevent inflamed gills resulting from physical injuries.

Steer clear of items and rocks with sharp edges and pointed tips. You will want to examine every piece of tank decoration before adding it to your betta tank. If you spot any rough edges, be sure to sand them down, or replace the decor entirely with an appropriate substitute. Check out this list of betta-friendly plants for inspiration!

In short, selecting betta-friendly tank decor can protect their delicate gills and flowing fins from rips and tears. This is one of the simplest, yet most effective ways of preventing inflamed gills.

Maintain Optimal Water Parameters

Maintaining optimal water parameters prevents most of the infections and illnesses that can cause inflamed gills in betta fish. Gill flukes, bacterial gill disease, and ammonia poisoning are all conditions that can be prevented by making sure that your betta’s habitat is clean.

Parasites and bacteria thrive in ammonia-rich environments, so it is crucial to perform frequent water changes to keep ammonia levels low. Testing your water frequently can also help you steer clear of fluctuations.

A myriad of test kits exists on the market for this purpose. We recommend getting a master kit that tests for the level of ammonia, nitrogen, and nitrates in the water.

Isolate New And Sick Fish

Fish-to-fish transmission of illnesses happens more frequently than one would expect. For instance, Bacterial Gill Disease can be transferred from a sick fish to your healthy betta. 

There are two things you should do to prevent diseases from spreading between your fish. First of all, you should quarantine all new arrivals for 14 days. This gives you enough time to observe your new fish for signs of infection before adding them to your display tank.

Secondly, you should place all sick fish in a hospital tank. Using a hospital tank not only prevents your unhealthy fish from coming into contact with their tankmates, it also allows you to dose your tank with medicine without needing to worry about its impact on other fish.


Inflamed gills are a potentially fatal condition as they can stop your betta from breathing efficiently. Fortunately, they are relatively easy to treat, and much easier to prevent! We strongly advocate for prevention over cure, as it is a more reliable way of keeping your bettas healthy!

Did you find this article helpful? If you know someone who could benefit from this article, do share it with them! We’d love to help as many people as we can.

Have you ever dealt with inflamed gills on your betta fish? What do you wish you’d known? – Let us know in the comments below!

Wanda is a second-generation aquarist from the sunny tropics of Malaysia. She has been helping her father with his freshwater tanks since she was a toddler, and has fallen in love with the hobby ever since. A perpetual nomad, Wanda does her best to integrate fish-keeping with her lifestyle, and has taken care of fish in three different continents. She loves how it provides a nice break from the hustle and bustle of life.

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