Betta Flaring: 7 Reasons Why They Do This & How To Detect It

Betta Flaring
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Last Updated: February 27, 2023 by Flora Gibbins

When you keep Betta fish, you get a front-row seat to the quirky world of these lovable fish. One of the many behaviors you’ll notice is a Betta fish flaring its gills. Male Bettas especially engage in this behavior, and it can seem odd to see it happen in an empty fish tank.


What does it mean when your Betta fish flares its gills? And is it a good or bad sign? We’ll reveal the answers to these questions and more in the article.

Betta Fish Gill Flaring – What It Is

Betta flaring happens when a Betta fish flares or puffs up its gills and fins in such a way as to make itself appear larger than it is.

You might see it happen when there are other Bettas in the tank or male Betta fish share a tank with female Bettas. Additionally, it may occur even though your Betta doesn’t share its fish tank with other tank mates.

Reasons Why It Happens

There are some reasons your Betta fish may flare its gills. We’ll discuss them in more detail below:

Territorial Instinct

Territorial Instinct

Bettas are territorial fish and don’t take kindly to drop-ins in their patch from other Betta males.

Therefore, in their natural habitat (rice paddies, ponds, etc.), these fish will protect their patch at all costs when mates and food are scarce (in dry seasons). A Betta fish will flare its gills to make itself look menacing when faced with an intruder in its territory.

In the worst-case scenario, it’s a form of intimidation that’ll convince the intruding fish to back down before the situation takes a violent turn.

However, these fish don’t get the moniker “Siamese fighting fish” for nothing, so a fight, sometimes to the death, might ensue. For the preceding reasons, it’s a terrible idea to put two male Bettas in one tank, especially a small tank without ample hiding spots for the fish to retreat to. You’ll end up with two dead Betta males otherwise.

Mating Ritual

Mating Ritual

If you keep Betta Splendens of the opposite sex in the same tank, then you can expect to see the male and female Bettas flare their gills at each other at some point.

In the wild, male Bettas flare in this way as a form of competition, with female Bettas choosing one fish out of many suitors. Once you notice a bubble nest on the water’s surface, you can take that as confirmation that the two fish are flirting with spawning in mind.

However, relations between male Bettas and their female counterparts can become strained, so the gill flaring may not always signify a mating dance. You’ll need to keep an eye on the two fish for signs of aggressive behavior (on the male Betta’s part) and separate them if the need arises.

Newly Arrived In the Tank

Shy Fish Syndrome Inside New Tank

When you introduce a Betta to a new tank, the little critter may feel disoriented by its new surroundings. Therefore, you may notice it is constantly flaring its gills as a response to unfamiliar stimuli. While this is entirely normal behavior, it isn’t good for your Betta and may result in a weakened immune system.

However, once your Betta fish has had a look around, checked out all the hiding spots in the tank, and become acclimatized to its new surroundings, the flaring behavior should subside. You can help things along by staying away from the Betta tank during the acclimatization period. This will reduce Betta flares.

Your Behavior

Betta fish flaring may occur when you hang around the tank too often during its early days. In other words, your new pet doesn’t recognize you as its owner or a benevolent creature who’ll ultimately provide it with sustenance and maintain its health.

From your Betta‘s point of view, you’re a huge predator and a threat to be driven away.

For example, when cleaning the tank, the Betta may flare at your fingers as they move through the tank water. Therefore, to get your Betta fish to stop flaring, you’ll need to watch your behavior during its early days. When cleaning the tank, try not to disturb the fish as much as possible.

Go about with the cleaning duties carefully and, if possible, refrain from removing the fish. Your fish will get used to the routine eventually.

Betta Vision

Betta fish eyes and human eyes are completely different in terms of how they view the world. While we see objects more clearly, Bettas rely on shapes and colors to make out your presence in the room. Moreover, these fish are acutely aware of vibrations in their environment.

You may find that your Betta will flare at you as you move around a room. In this case, the flaring occurs because your Betta feels spooked by the movement. Keeping the noise down to a minimum should prevent constant flaring when you’re in the same room.

Fun Fact: Learn more about this betta’s ability by reading this article we posted — Can Betta Fish See Color: Interesting Facts About Its Vision and tell us what you think!


Believe it or not, sometimes, how often a Betta fish flares comes down to the fish’s personality. Some fish are just naturally more excitable than others and may flare up at the sight of their owners.

Unfortunately, you can only tell if your Betta is happy to see you or is responding to a perceived threat after the fish has become acclimatized to its environment. You might need to wait before concluding whether your Betta’s flaring is a good or bad sign.



You might notice your Betta fish flare at its reflection because your Betta buddy can’t differentiate its own reflection from another fish.

When the Betta sees itself, it’ll assume a defensive posture, thinking there are two males in the tank. You’ll have to do something about the tank reflections because too much flaring will stress your fish out. Here are a couple of things you could do:

 Adjust Room Lighting

As a first step, try adjusting the lights in the room.

Bright lights create reflections in the glass of the Betta’s tank, which may cause male Bettas to think they’re dealing with an intruder on their turf. Turning down the lights in the room should fix the issue. However, if it isn’t possible to reduce the room’s brightness, then consider moving the tank to another dimly-lit room in the house.

It’s also a good idea to reduce the tank’s lights (if your Betta’s tank has them). Betta fish aren’t used to bright environments in the wild and prefer an environment with lots of shade and cover to avoid predators. If the tank is too bright, your Betta will frequently hide to avoid the light, in addition to flaring when it sees its reflection.

Provide Cover

Another thing you can do to prevent a Betta from flaring at its reflection is to cover up the sides of the tank.

You can get some aquarium-specific adhesive paper from your local fish or pet stores and use that. Alternatively, craft paper should do the trick as long as you avoid bright colors. Finally, you could try using some fabric that works well and fits the tank sides.

Benefits of Flaring

As mentioned earlier, Betta flaring isn’t all bad. So let’s take a look at some benefits Bettas can get from flaring:

Reduces Boredom

Bettas get bored. Usually, it can be enough to buy some toys for the tank and interact with the fish from time to time. It’s also possible to engage in mirror play to keep your Bettas engaged or shake them out of a depressive funk.

You have to hold up a small mirror for a few moments until your Betta fish catches sight of its reflection, and the fish will flare up thinking there’s an intruder. Keep in mind that you’re deliberately making your Betta perform a stressful activity and should keep it to a minimum.

 Stretching Exercises

While territorial aggression and mating are valid reasons for gill flaring, Betta males that live alone won’t need to display an aggressive response to intrusions or attract a mate. Instead, they may engage in the behavior simply to get a nice stretch.

Doing so will keep your Betta fish healthy and in good shape. Except for cases of excessive flaring, you might not need to feel concerned. This type of flaring is beneficial to your Betta fish because it lets it shake off muscle stiffness.

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Frequently Asked Questions

Is flaring bad for Bettas?

While there are a few cases that make flaring beneficial for these fish (for example, indulging in natural behavior like stretching), when Bettas flare excessively, it can mean serious trouble for their health. Flaring can be stressful for the fish as aggressive behaviors tend to be for most living things.

You can think of flaring as a state of tension. Being constantly tense is terrible, so the underlying cause needs to be dealt with as soon as possible. Otherwise, your Betta fish will be open to attacks on its immune system, causing bacterial infections like fin rot.

Do female Betta fish flare their gills?

 Flaring isn’t limited to male Betta fish—female Bettas do it. They may flare at other female Betta fish, but only in a semi-aggressive way. However, you’ll never find the females flaring at their reflection; only male Betta fish do that.

Additionally, it’s possible to create a sorority of female Betta fish by keeping more than one in the same tank. If you decide to introduce a male Betta into the mix, observe for signs of bullying.

Will Bettas recognize their owners eventually?

Yes! Once a Betta fish learns that you’re the source of its food, it’ll begin to dance when you approach the tank. You can also look forward to your Betta swimming to the surface to wait for its food during feeding time.

Additionally, when you’re cleaning the tank, these curious fish may approach you and possibly nibble at your fingers gently.


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.

When you see your Betta flaring its gill flaps, you might want to look into the underlying cause and correct the situation, as when these fish flare repeatedly, their health can be negatively affected. However, flaring also has positive benefits like snapping your fish out of boredom or getting them much-needed exercise.

As long as it happens in moderation, your Betta should be fine.

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