Why is my betta fish flaring its gills?

In this blog we will discuss everything related to bettas gill flaring behavior.You will understand this behavior much better. You will learn how to help your fish deal with this behavior.


In this blog

  • Why is my betta fish flaring its gills?
  • Why do betta fish flare?
  • Do betta fish flare when they’re happy and excited?
  • Do bettas flare due to aquarium lights?
  • Is gill flare common only among male betta fish?
  • Do female bettas flare at each other or other tank mates?
  • Is flaring an indication of breeding?
  • Is flaring healthy for betta fish?
  • Summary 
  • Frequently asked questions
  • Reference

Why is my betta fish flaring its gills?

If bettas are flaring, it is nothing but an act of intimidation and is meant to show dominance, to look bigger and dominating in their aquarium.

The most common cause for betta fish to flare is an intruder in their territory. 

By inflating their gills widely, a betta fish appears to be twice its size, which can scare off an intruder.

The flaring can be caused by another aggressive fish in the aquarium, by a person walking by, or by a reflection in the glass.

A betta fish may flare up a little each day, but if it lasts longer than a minute or so, it can stress the fish.

Why do betta fish flare?

Threat to bettas territory by another male betta

For centuries, bettas have been bred to be aggressive and don’t hesitate to show violence to anything they see as an intrusion into their territory.

Betta flaring is a result of fish sensing that their territory is threatened by another tank mate.

The betta fish is known to be a very territorial species. When the paths of two male bettas cross,they are often involved in the flaring act. By this action, they declare their rights to their territory.

Therefore, it is not advisable to have more than one male betta fish in the same aquarium unless there is enough space to share or a tank divider.

In the wild, betta fish flare for some time and eventually one of them recedes, but captive conditions offer limited concealment options, which inevitably lead to flare, combat, and thus injury.

Aggressive bettas tank mate

You should be aware that bettas are aggressive and difficult to keep with other fish or their own kind. Even if your betta seems calmer, he will eventually flare up at other tank mates.To avoid aggression and unhealthy flaring, choose your bettas’ tank mates carefully.

Betta fish require proper tankmates. Otherwise, the environment can collapse. New enthusiasts need to monitor the community so that bettas aren’t chased or fish don’t try to bite beautiful fins. 

Betta gills can flare from stress. Enthusiasts should carefully observe the behavior of the tank in order to minimize the occurrence of flare.

However, there are times when you can’t do anything about your pet’s aggressive attitude. This is because some bettas are naturally more aggressive than others.If your betta doesn’t want to share space, consider putting it in another aquarium.

Bettas seeing their own reflection in the aquarium glass

If your betta is alone in the tank but is still puffing or flaring out his gills or fins, he probably sees his reflection in the glass. This is because bettas didn’t not pass the mirror test,so they often see the mirror as another fish and see it as a competitor.

Male betta often mistakes aquarium glass reflections for rival male fish and tries to protect their territory by flaring. This is very common when moving to a new tank and most often stops after a few days of getting used to the new environment.

Do betta fish flare when they’re happy and excited?

Some fighting fish or betta fish naturally flare up when they are aroused by some healthy stimulus, such as during feeding or when you enter a room to play with them. This may be due to the individuality of each individual fish and should not cause you much concern.

Do bettas flare due to aquarium lights?

If you find that your betta is flaring at his own reflection, try doing something to help them. For example, start by adjusting the lights. You can move the lighting in the room, or if that’s not possible, try moving the tank to a new location. 

If you can’t move the tank, try adjusting the tank lights.You can also add live plants and filter out the light. Floating plants are often preferred.

If the above options don’t work, try closing the sides of the tank while leaving the front open.Outside,you can stick thick paper or newspaper. Use neutral or warm colors so that your betta doesn’t tire his eyes with bright colors

Is gill flaring common only among male betta fish?

A flaring is a display of extended gills that occurs when a fish feels threatened. 

This flashing or flaring behavior is common among male bettas when the fish are defending established territories or mating partners. Luckily, the fight is mostly limited to the display of flared and extended fins.

Male betta fish might flare at female bettas as well.You can create hiding space using rocks, aquarium caves, or aquatic plants to avoid this.

Do female bettas flare at each other or other tank mates?

  • There seems to be a debate online about whether a female betta will flare their gills. 
  • Whether or not a female betta will flare is a matter of mood. Betta females can also flare up at each other. 
  • The main difference between them and betta males is that females are rarely aggressive, depending on their character traits, some females may not flare when seeing their own reflection.
  • Betta females sometimes quarrel with each other, but this is rare. Every once in a while, a small nibbling of the fins may occur among the females.

Is flaring an indication of breeding?

Another reason males flare up is when the breeding season begins. When you first introduce a female to a male, the male flares up to impress the female and establish dominance. Female bettas do flare up in response.

Is flaring healthy for betta fish?

Having gained some understanding of the nature of bettas, you now know that the act of expanding or flaring the gills is their normal behavior.

A small amount of flaring does not hurt your betta fish and can be very good for him in that it provides stimulation and exercise. 

However, too much flare causes stress, weakens immunity, and makes your betta fish more susceptible to health issues or diseases.

Betta fish with too much flare can be susceptible to bacterial infections, diseases and parasites.

Some betta fish will even refrain from eating in the presence of an intruder, which can lead to health problems in the fish.

Bettas should not flare more than a total of 20 minutes a week. Beyond that, your pet will be stressed.If you find that bettas are flaring for a total of 20 minutes or more a week, you need to find a solution to stop this over-behavior.


Bettas puff out their gills when they want to open them. The bulge of the gill exposes its membrane.

Betta fish use flares to make themselves appear larger and more intimidating to competitors.

Flare behavior is not always a sign of attack or combat. You may notice that your betta is flaring during the day, and it makes sense for your fish to do this for a short time during the day.

The conflict between two wild male bettas rarely ends in death. Usually one man is defeated and retreats. Due to the small habitat and few escape routes for fish, confinement of home aquariums presents a variety of challenges.

Flaring in itself is not bad for betta fish health as it plays the role of exercise for their muscles.

It’s normal for betta fish to flare up occasionally, as it keeps them in good shape. You can even stimulate them to flare for about 2 to 3 minutes a day.

Check for all stressors such as improper tankmates, intense light and reflections.Make sure you fully understand the betta’s personality and act quickly to avoid stressful situations.

Frequently asked questions

Is flaring an expression of anger?

Fighting of gills is perfectly normal, but this behavior is not always an expression of anger. When a fighting fish flares up, it could also mean that your fish is stretching its muscles.

Is it a good idea to keep two male bettas together?

It is not a good idea to keep two or more male bettas in the same tank unless there is enough space to share.

Do bettas flare at owners?

Sometimes betta fish will flare up at their owners or even at their food. This is not a good sign as it can stress them.Stress weakens their immune system, and makes it vulnerable to attack by bacteria and parasites.