Why Do Betta Fish Flare Their Gills? 5 Common Reasons! (2023)

Bettas are some of the smartest fish you can keep as a pet. They are responsive, quirky, and quick to learn different behaviors.

You will sometimes find your Betta fish chilling on the substrate in the water tank or swimming around from corner to corner.

However, there may be a time there you might find your Betta fish aggressively flaring its gills.

So, what does it mean when a Betta fish aggressively flairs its gills? Is it friendly behavior? Do only male Bettas do it? Should you be concerned?

When you buy a new Betta fish for your fish tank, it is possible that it flares its gills in the beginning.

This can be confusing, especially for a new fish owner.

Table of Contents

Let’s explore the reasons why a Betta fish might flare its gills:

Possibly an Act of Claiming Territory

By nature, Betta fish are incredibly territorial species.

Due to this tendency, two Betta fish may flair their gills when they come across each other.

This is an act of claiming territory. This is why two male Betta fish cannot live peacefully in the same fish tank.

They flare their gills because they automatically consider the other Betta fish as an intruder.

Due to their temperament, they do not prefer other male Betta fish entering their territory; hence, the display of gills (like a show of strength to keep the other one in limits).

(Video) Why is my betta fish flaring its gills?

Male Betta fish do not get along

If a male Betta fish spots another male Betta fish, the automatic response is to puff out its gills to appear wider.

This makes them appear twice as big in hopes of intimidating the fish that entered their territory.

It is not necessary that male Betta fish flare their gills at other Betta fish only. They could display this behavior with any other aggressive fish that might be in their tank.

This is also a possible reaction to anything they are scared of or even a human passing by.

Betta are Territorial by nature

Betta fish display territorial aggression because that is how they have lived for centuries in their natural habitat.

This particular fish species does not hesitate to display violent behavior towards any intruder that enters their territory.

Betta fish are typically more threatened if the trespasser displays the same or more amount of aggression towards them.

As an automatic response, they will try to match their competitor’s aggression level by flaring their gills.

In a wild setting such as a pond, Betta fish flare their gills at each other pretty regularly if they feel that someone has intruded into their territory.

However, this goes on for a while till one of the aggressive parties eventually backs off.

When it comes to fish tanks in our homes, it is wise not to place male Betta fish together unless they have a substantial amount of space.

Remember, each mature Betta fish need at least four to five gallons of water to be happy.

Being in fish tanks gives them a limited space, with very few hiding places. This makes them more insecure than if they were in the wild.

As a result, they end up fighting more and also causing each other injuries.

Therefore, if you want to place two male Betta fish in a single fish tank, it should be at least a minimum of 8-10 gallons (bigger would be better).

This allows them to live in peace by forming their territories.

(Video) Is Betta Fish Flaring Bad? What Does It Mean? Pros and Cons of Flaring.

In terms of gender, a male Betta fish can flare its gills at another male or even a female intruder.

However, most issues happen between male Betta fish.

In some cases, you may notice Betta fish refusing to eat if the presence of a trespasser stresses them.

This leads to multiple health and stress-related issues for them.

Your Role as a Fish Owner

As a fish owner, you should choose your Betta Fish’s tank mates carefully.

You should also decorate the fish tank with live plants, rocks, and other decor pieces to give them several hiding places.

Just a few efforts on your part will give your Betta fish the personal space that it needs in order to be happy.

It will keep them stress-free and reduce aggressive behavior.

However, there may be some cases in which your Betta fish has extra temper issues.

Regardless of your efforts, you may not be able to stop it from behaving aggressively.

In that case, you should consider giving your pet a separate tank, so it does not bother the other fish.

Glass Reflections Can Be the Cause

If you notice your Betta fish flaring its gills even when it is the only fish in the tank, it is either flaring them at you or its own reflection in the glass.

It is very likely for a Betta fish to be intimidated or aggressive towards its own reflection.

Since they do not understand the concept of mirror reflections, they perceive their own reflections as an intruder in their territory.

If you find your fish in a similar predicament, you can add a few more plants in the tank to avoid your Betta fish seeing any reflection that may stress it out.

Another great thing to do is add floating lights to your fish tank so that that lighting reflections keep changing.

(Video) 10 Signs of Happy Betta fish

This will stop your Betta fish from focusing on a singular point that may be stressing it out.

Once your Betta fish gets used to the surroundings in the fish tank, it will grow more comfortable with its own reflection in the glass.

This can take up to 3 weeks, depending on the behavior of your Betta fish.

In some cases, you may have to dim the lights above the fish tank to speed up the familiarization process.

If your light is placed at the wrong angle, it can enable your Betta fish to see their own reflection, which can make them uncomfortable for a very long period of time.

Hence, it is best if you take special care of the lighting in and over your Betta fish tank.

Entering the Mating Period

Another known reason for Betta fish to flare their gills is when they are entering their mating period.

When a male and a female Betta fish decide to mate, it is the male’s job to impress the female.

A male Betta fish does this by flaring its gills in order to impress his female companion.

Other than impressing, it is also a power move to express dominance.

A female Betta fish may respond to the male by flaring as well; however, this behavior is not that common.

Before proceeding to the actual mating ritual, you may notice the male Betta fish flaring several times to keep the female Betta fish interested.

Excitement (for Food)

Even though this is a pretty uncommon reason, it is still very much possible.

Some fish owners report they’re Betta fish flaring their gills when it’s time to feed them.

This display of gills is not aggressive compared to the one linked to territorial aggression.

If your Betta fish is playful, it may end up flaring its gills out of happiness or excitement.

(Video) BETTA FLARING EXPLAINED; Myths, Facts, Agression & Care

Does Gill Flaring have a Bad Impact on Betta Fish?

Based on what we have discussed so far, it is safe to say that gill flaring is something natural in Betta fish.

Regardless of being a natural behavior, there are some problems attached to it.

You should be concerned if your Betta fish constantly flares its gills because it can be bad for its health.

While some may are you that it is a good exercise for their muscles, it is also a display of stressful and aggressive behavior.

If your Betta fish is flaring its gills constantly, it means that it is under a lot of stress.

If you do not put in the effort to reduce these stress factors, it can eventually lead to your Betta fish developing a weak immune system.

As a result, it may become prone to infections and diseases that may or may not be fatal.

Other than this, if your Betta fish stays under constant stress, it may become more susceptible to lack of appetite, loss of color, lethargy, and other stressful symptoms that are common in Betta fish.

These signs usually point towards some form of sickness that is not a good sign of health in your pet fish.

If you feel that your Betta fish is showing any of these symptoms, you should immediately narrow down and eliminate the stress factor or consult a vet for professional advice.

Anything such as glass reflections, lighting, or violent tank mates can be a source of extreme stress for your Betta fish.

On the other hand, if your Betta fish flares its gills occasionally, it is not much of an issue.

It would only help keep your Betta fish physically healthy.

The Bottom Line

In general, the act of flaring is meant to be an intimidating act to fend off any intruders.

It is absolutely okay if your Betta fish flares up occasionally and not all the time because it keeps them in good shape!

Other articles you may also like:

(Video) 10 ways to tell if a betta fish is dying - Betta fish informational video

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  • Why Is Betta Fish Swimming Erratically?
  • Why is Betta Fish Swimming Sideways (Swim Bladder Disease)?
  • Can Betta Fish Jump Out of a Tank?
  • How Many Betta Fish Can Live Together?
  • How Long Can a Betta Fish Live In a Fishbowl?
  • How Do Puffer Fish Deflate?


Why do Betta fish flare their gills? ›

Flaring is part of a Betta fish's natural behavior and is an aggressive display meant to ward off other fish from encroaching on the Betta's territory. You'll observe the behavior predominantly in male Bettas, though female Bettas may do it from time to time.

What are the benefits of betta flaring? ›

Flaring is very stressful for your betta. Too much of it is harmful. Some flaring is good for bettas. It enables them to stretch, giving them a workout of sorts and keeping them in shape.

What makes a Betta fish stressed? ›

High ammonia or nitrate levels, low oxygen levels, improper temperature or a high or low pH can cause stress.

Why does my betta keep flaring at his reflection? ›

A: Male bettas will often mistake their reflections in the aquarium glass for a rival male fish and will attempt to defend their territory by flaring. This is really common when moving them into a new tank and in most cases they will stop after a couple of days as they get used to their new surroundings.

What does a happy betta look like? ›

A happy betta will swim around their tank daily. Sometimes they will move almost lazily about, and other times they'll flit from side to side quickly. If the betta appears to have no trouble swimming and isn't leaning to the side or struggling, your betta is healthy and happy.

Does my betta recognize me? ›

Betta fish may not "love" their owners in the way that a dog or cat would show affection, but they will show a clear interest and affiliation with their owners. Bettas are also known to have good memories and can remember people despite not seeing them for several weeks or more.

How do you cheer up a betta fish? ›

Talk to your Betta.

You may notice that your betta swims more actively when you talk to the tank. You can also move your finger around on the glass of the tank, or wiggle it at the surface of the water. He will try to jump toward it. Just be careful not to let him jump out of the tank.

Is it stressful for bettas to flare? ›

Flaring is bad for betta fish because it's a stressful behavior. It can occur for many reasons, but aggression is one of the major causes of this behavior in your betta. To some extent, flaring is beneficial as it allows your betta to have the required stretch, but too much flaring is alarming and shouldn't occur.

Why is my betta glass surfing? ›

“Glass surfing” is when a fish – such as betta fish, gouramis, and cichlids – repeatedly swims up and down along the tank walls. It could be caused by stress, boredom, defense of territory, and other reasons.

Do Bettas need toys? ›

Yes, betta fish love having toys in their tank. They're a naturally curious and inquisitive fish that want to explore their surroundings. Betta's love to interact with their environment and can get bored if they don't have enough stimulation.

Why is my betta fish darting around the tank? ›

This behavior can also be caused by fish fighting. Make sure another fish is not harassing the distressed fish. If this is not the case, test the water levels for ammonia, nitrite, nitrate, high pH, and incorrect temperature.

How much should a betta flare? ›

If possible, try to limit your betta's flaring to no more than 20 minutes total each week. Any more than that and your pet will become overly stressed. Ensure your betta fish tank has everything necessary to keep him happy.

What do Stressed betta fish look like? ›

Strange Swimming: When fish are stressed, they often develop odd swimming patterns. If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress.

How many gallons does a betta fish need to be happy? ›

The ideal sized tank for a betta is 5 gallons or larger for a single male or female betta. There are a number of reasons why 5 gallons should be the minimum size you consider, some of which are quite technical. To keep things simple, I'm going to give you the most compelling reason to choose a 5-gallon tank…

Can a single betta fish be happy? ›

Betta fish are naturally territorial and should not be housed with any other betta fish because they will fight and injure each other, often resulting in death. They are unlikely to get lonely in their tank; however, if they are in a small tank, they may get bored.

How many times a day do you feel a betta fish? ›

How often do you feed a betta fish a day? Starting with at least two meals a day, provided your tank is at the correct temperature, space your meals at least 6-8 hours apart. You can feed up to three meals a day if your fish is currently breeding or at the warmer end of the temperature range (80-82F/27-28C).

Can I touch my betta fish? ›

Betta fish should rarely, if ever, be petted. It's not good to pet them, as it may remove their natural slime coating, making them prone to certain diseases. Also, never touch them with dirty hands, as bacteria can easily be transmitted through direct contact.

What does an unhealthy betta look like? ›

The appearance of yellow-ish dust covering the betta; lethargy; loss of color; loss of appetite; clamped fins (held close to the body).

Will betta fish bite you? ›

Their teeth are too tiny and unable to exert enough force to pierce human skin, which is too thick for them to handle. If bitten by a betta fish, a person will typically only experience a minor tingling or prickly sensation rather than pain.

What do betta like in their tank? ›

Your Betta will love swimming in a tank which contains caves to hide in and plants that provide plenty shady areas. Betta's enjoy lounging on leaves and have comfortable places to hide and sleep. It's important you check ornaments for spots that could snag or tear your Bettas delicate fins.

What do betta fish likes? ›

Bettas have upturned mouths and primarily feed on the water's surface. A good diet consists of dried bloodworms, brine shrimp or daphnia. Commercial betta food or pellets are best because it combines all three foods, in addition to vitamins and minerals. This improves the betta's brilliant coloring and longevity.

How can you tell if a betta fish is stressed? ›

If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress. Talk to your veterinarian about treatment and look into what may be causing the stress and alleviating it.

How do you know if your betta fish is struggling to breathe? ›

That's why if you see betta fish gasping for air at top of tank, it means they're trying to breathe. They sometimes do it randomly. But that's not a reason to ignore it. If you look closely and see them hyperventilating, then that means they are having a hard time breathing.

Why is my betta fish opening and closing his gills? ›

A: When a fish opens and closes its mouth repeatedly and rapidly, that can indicate that oxygen levels in the water are too low. Fish breathe through their gills, so opening and closing their mouths enables more water to flow over the gills, taking more oxygen to the fish's body.

What calms betta fish? ›

Use tannins.

You can use either aquarium safe woods or Indian almond leaves in your tank, as they both naturally release tannins. This darkening of the water will mimic your betta's natural environment, which will make him feel less exposed and less stressed.

How old are betta fish when sold? ›

Because a Betta purchased at a pet shop is often one year old already. Males, in particular, are allowed to fully mature, so their fins and colors are well developed. Females may be sold at a bit younger age, but they will generally be at least six months old when offered for sale.

How do I know if my Betta fish is getting enough oxygen? ›

Signs of Low Oxygen

They will swim less vigorously and even eat less often. As oxygen levels drop further, the fish will begin to show labored breathing and more rapid gill movements as they desperately attempt to get enough oxygen from the water by passing more water over their gills.

Do Betta fish like light in their tank? ›

Do Betta Fish like Light? Yes, they won't like anything too intense, but a standard aquarium light is perfect. Bettas also love aquarium plants, which need an aquarium light to grow and survive.

What do healthy betta gills look like? ›

GILLS. Gill plates that can open and close with ease. In healthy bettas, the gill plates remain closed during normal activities and can easily open and close when flaring or flushing out the gills.


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