Why Is My Betta Flaring? 7 reasons Why

Flaring their gills or puffing them up makes Betta Splendens fish look larger. When bettas become excited by external stimuli, they often flare.

Something like feeding time or a new toy, or a reaction to an intruder triggers this. Flaring is a normal behavior and not a cause for worry unless it is excessive.

Betta fish, particularly males, flare their gills for various reasons.

betta flaring atf

#1 Territorial Instinct

Bettas have a strong territorial instinct and will flare their gills at an intruder. They do this to make themselves appear larger and more dangerous to the interloper.

This intimidation may drive off the other fish and save the day. If it does not, a fight will ensue.

Betta fish are called “Siamese Fighting Fish” for a reason. They are aggressive and will fight to injury or death when their territory or mate is threatened.

The flare is a display of the fish’s size, shape, and color, and it is quite impressive to see.

#2 Mating Ritual

Flaring their gills is also part of the betta mating ritual. Male bettas in the wild will flare their gills at one another in competition.

The female will choose a suitor from those on display.

Males and females will also flare at each other during courtship. Other courtship behaviors might accompany the flare, including tail flapping and fin nipping.

If the male and female flare their gills at each other, ensure it is merely flirtatious behavior. You will need to separate them if it is aggression.

If you spot a bubble nest on the water’s surface, this is a sign the flares were part of the mating dance. Aggression may still come into play between mating partners, so be observant.

Do female betta fish flare?

Female bettas flare, although less often than males. They flare as part of the mating ritual and to appear more intimidating when threatened.

Female bettas also flare to deter males, as well as defend territory. While they are not as territorial as males, they do have their areas and will defend them.

Female betta fish can live in a group of five or more in a large enough betta sorority tank.

If you see your female bettas flaring at one another, you may need to separate them. They might not have enough space (at least 5 gallons per fish is best) or hiding places.

#3 Newly Arrived In the Tank Or Tank Changes

Betta flares are also a sign of feeling overwhelmed by unfamiliar stimuli. When you first introduce them to a new tank, they may feel a little thrown off their normal pattern.

This is a normal reaction and not to be worried about. However, it isn’t good for your betta if it goes on too long.

Some aquarists use dark paper or cloth on the back of the tank to keep their betta from seeing outside. Bettas are not used to bright environments and need lots of shade and cover.

Once your betta has become acclimatized, the flaring behavior should tone down.

Your best bet is to stay away from your betta’s tank as much as possible so as not to add to its stress. Even walking across the room can send disturbing vibrations during these early days.

#4 Tank Mates

betta flaring at tank mates

Bettas do well with peaceful, smaller, drab tank mates. They will flare, however, if they are not used to them.

Give your fish some time to get used to their tank buddies. Watch for other signs of aggression to prevent fighting and injury.

Make sure your fish have plenty of escape routes in the tank in case someone has an aggressive attitude. Making sure you have enough space for all your fish cannot be emphasized enough.

#5 Getting Used to You

Give your betta time to adjust to its new surroundings. While it is getting used to things in its new tank, make sure you stay away except for necessary maintenance.

Your betta won’t recognize you at first and will feel threatened. Use a piece of glass or acrylic between you and the tank to block its vision.

Don’t make sudden movements or too much noise. The vibrations will bother your fish.

Do not bother the fish, especially when you clean the tank. Do not remove the fish from the tank, if possible.

Once your fish is used to the surroundings and routine, you will be able to interact with it more naturally.

Many bettas will even do a little happy dance when their owners come to feed them. They are apparently very clever and food-oriented fish.

Tank Cleaning

Perform regular tank maintenance routinely. Do not move objects or plants around in the tank around for no reason.

Clean the tank as unobtrusively as possible in order to prevent stress in your fish. It will flare less and be healthier.

#6 Personality

betta flaring behavior explained

Some bettas flare more than others. Helping your fish feel safe will help prevent excessive flaring.

If your betta fish shows signs of stress, like not eating or hiding, investigate the cause and take action.

Provide Them With Plenty of Room

Another factor in your fish’s comfort level is how much space they have. Give them at least a ten-gallon tank instead of five.

Bettas need a minimum of five gallons per betta and plenty of swimming room. They are active fish and need a lot of surface area for breathing and nesting.

Bettas thrive in a spacious environment with lots of hiding spots. Floating logs, caves, and plants provide plenty of resting spaces and hidey-holes.

A larger tank allows them to indulge in natural behaviors and makes for healthy fish.

#7 Other Bettas

Betta fish detect color and easily spot rivals in the wild. Your betta wants to be intimidating enough to prevent a fight with a potential threat.

Flaring of the gills is one form of communication between betta fish. It can signal aggression, dominance, or even a mating intention.

Betta fish communicate through color, pheromones, vibrations, sounds, posture, and swimming. Look to see what other signs are present to decide why your betta is flaring.


A betta has a hard time discerning its own reflection from another fish. Seeing its own reflection may make it aggressive and trigger a flare.

Territorial aggression is a natural behavior, but not one you want to make worse with reflections.

One way to help prevent this is to lower the room lighting. This has the effect of lessening reflections in the aquarium glass.

The betta will not see a reflection and think there’s an intruder. Dimming the aquarium lights is also helpful.

Some fish keepers cover the sides of the aquarium, creating a front viewing pane.

Providing many breaks in vision and hiding spots will help your betta feel safer. They will exhibit fewer aggressive behaviors.

Live aquatic plants are terrific for this. They improve water quality as well.

Benefits of Flaring

betta flaring benefits

Reduces Boredom

Flaring their gills reduces boredom, somewhat like a dog barking at the mail carrier.

Provide hollow floating logs, resting platforms, and aquarium caves to stimulate your betta. There are also toys available to keep your betta tank interesting.

An aquarium well-planted with live plants provides wonderful enrichment for your betta.

Stretching Exercises

Flaring provides your betta with a good stretch. It will help it keep its muscles toned and circulation going.

Some betta owners hold a mirror up to the tank to inspire their fish to flare and get a brief stretch in. More than once a day of this form of exercise is not recommended.

Pet stores even stock exercise mirrors for this purpose.

Provide your pet with decorations and caves to explore to provide exercise. Plenty of exercise opportunities also help prevent obesity in your fish.

When Is Flaring Excessive?

Flaring once a day or so is not bad for your betta. Excessive flaring is stressful and hard on your fish.

This stress will leave them open to parasitic and bacterial infections. Pale coloration, lack of appetite, and lethargy may show a high-stress level.

If your fish is flaring frequently, you need to look at what is causing the flaring. Make sure your fish is not overcrowded, bullying, or being bullied.

Flaring is an aggressive response for this territorial fish. Providing distractions in the fish tank will help reduce these occurrences.

Wrapping It Up 

Gill flaring is an intriguing behavior that bettas engage in to communicate. Whether to warn off interlopers or to flirt, a flaring display can be beautiful.

Mainly male bettas flare, but female bettas also do it when mating or their territory is threatened. 

When you see your betta flaring, do not be alarmed. Look into why they might be flaring and rectify any problems such as bullying or overcrowding. 

Flaring can provide exercise and something entertaining to do for your fish. Look for other signs to ensure they are not flaring too often or for negative reasons. 

For more information on interesting betta behavior, check out this page!

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Wesley Oaks has a background in web publishing and decided to combine his skillset with his enjoyment of betta fish. When he isn’t working behind the scenes for Betta Fish Bay, he’s homeschooling his kids and soaking up quality family time.

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