Betta Fish Flaring Gills and Puffing Up? Here’s Why

Also known as a Siamese fighting fish, bettas are known for flaring. By puffing up their gill flaps wide open, these small fish appear bigger in size. Let’s get down to why your betta fish is flaring gills and what you should do to stop it.

Betta fish flaring gills and puffing up shows might and aggression. They do this to scare away intruders, attract mates, exercise, or express excitement. They also do so to their reflections. This is normal with bettas, but it can also be a sign of distress if they have unsuitable tank mates.

Is betta fish gill flaring normal?

Yes, it’s normal for bettas to open the gills wide. They do so to appear larger than their actual sizes to scare an intruder. This occurs when movements occur near a tank, they see their reflections, or feel threatened by a tank mate.

Causes of gill glaringWhat to do
AngerAvoid agitation
Defense Avoid agitation
Excitement Do nothing. It’s good
Unsuitable tank matesRemove unsuitable tank mates
Response to reflectionsControl reflections
Exercising Provide toys
IntrusionApproach the tank carefully

They may also flare at the beginning of a breeding period. Male bettas will flare to show dominance or impress the female. The female, on the other hand, will puff up her gills in response. This continues until the female is ready to spawn.

Why is my betta fish flaring its gills?

There are different reasons why your betta is flaring its gills:

1. Anger

A betta becomes frustrated when its needs aren’t met. They love personal space, and flaring could be a sign of poor conditions in the tank. Unfortunately, too much flaring can weaken the fish’s immune system and exposes it to parasites and bacterial infections.

To prevent your betta from flaring often, provide a suitable environment to keep it happy. Ensure the tank is not crowded and there are enough hiding spaces in it. Add toys and decorations for fun and exercise.

2. Defense

Bettas become territorial and aggressive when they notice a threat. They flare to make an illusion that they are bigger than their enemies. Often, they are ready to fight them.

In some cases, fatalities occur when bettas fight. Both of them could end up injured or dead.

3. Excitement

Bettas also fare when excited. You may notice this every time you feed it or even play with it. New toys also make them happy. However, the excitement levels vary from one betta to the other.

A betta flaring when happy depends on its personality. Don’t worry if your betta doesn’t flare for the same reasons.

4. Unsuitable tankmates

Bettas can co-exist peacefully with tank mates they are compatible with. Examples of such tankmates include glass catfish, white cloud, back molly, and swordtail. Hence, when introducing a new tankmate to your betta, ensure it’s friendly and accommodating.

It shouldn’t be chasing your betta around or nibbling on its fins since it may stress your betta. In response, it will flare and start a fight.

5. Response to reflections

Bettas are not good with reflections. When it sees its image, it mistakes itself for another fish, whichmakes it angry and irritated. It then gets territorial and starts a fight with its image.

Betta fish glaring gills

For this reason, avoid putting reflecting surfaces near the betta tank.

6. Exercising

Betta fish can be quite lazy. They can spend all their time resting or hiding and only come out when they have to eat.

Unfortunately, this makes them fat and unhealthy. Flaring is a form of exercise that keeps them stretched and their muscles toned. It also keeps them fit and active.

7. Your presence

There are different reasons why betta could be flaring at you. It doesn’t mean it’s angry at you. Fortunately, it’s common when feeding it or playing with it. Don’t worry, as bettas are wary of new environments.

The betta could also flare at you because of fear. This can occur every time you clean the aquarium or change the water. The fish is probably alarmed, and it’s a way of reacting to your presence.

Lastly, although bettas don’t see clearly, they are sensitive to colors and vibrations around them. When you are moving around the tank or playing loud music, it might get frightened and thus flare.

It may take a while before your betta fish finds comfort in a new home. Give it space to settle down and, after a while, it will get used to you.

How do I stop my betta from flaring?

There are several ways you can stop your betta from flaring. Knowing the exact reason for the flare would ensure you offer the best remedy.

Some of the ways you can prevent and stop betta fish from flaring include the following:

1. Remove incompatible tank-mates

When a tank mate is the cause of its flare, remove it and take it to another tank.  If your tank is small, the betta fish and its mate could have found it difficult to co-exist in the space. You may want to increase the tank size and add hiding places.

If this wasn’t the issue, separate the two into different tanks to ensure peace prevails. Remember, an angry betta is dangerous.

2. Control the reflections

First, find the source of the reflection. If it’s the location of the tank, move it to another spot.  You can change the lighting system in the room by moving the exterior lighting away from the betta’s tank.

Alternatively, you can adjust the lighting in the aquarium. Remember, betta fish can see in the dark, and don’t love bright lights.

If you can’t control the lighting, color the sides of the aquarium and only leave the front view pane clear. Use adhesive fish tank-specific paper. It should be thick and pale colored. Avoid shiny or brightly colored paper as it will irritate the fish.

You can also add live and floating plants to create more shadows in the water and minimize the reflections.

3. Relieve boredom

Bettas become bored when they are not stimulated. You can give them toys like Ping-Pong balls and add live plants, logs, and caves to their habitat to stimulate them.

You can also hold up the mirror for your fish to stimulate it. It will flare in the process. Just limit the time to around 1 min.

Do female bettas flare?

Yes, female bettas do flare. But, unlike the male ones, they are semi-aggressive. Males love to show dominance over one another. The female mostly flares for exercise and stimulation.

Depending on the species, some females might not even fare at the sight of their reflection.

Female bettas can thus co-exist peacefully in a sorority tank. Ensure the tank is big enough and has enough hiding spaces to accommodate the different fish. However, constantly monitor your female betta fish, and look out in case of any flares.

Is flaring bad for bettas?

Flaring can be good or bad for the betta. If you notice your betta flaring for a few seconds per day, it’s okay and perfectly normal. If prolonged and excessive, take the opportunity to have a closer look at their gills and fins and check out for any signs of susceptible conditions.

Bettas should, however, flare for at most 20 minutes a week. Anything more than that could weaken their immune systems, making them vulnerable to diseases caused by parasites and bacteria.


A little faring is good for your betta fish. However, if constant and persistent, it might lead to severe consequences. A flare is an aggressive response that shows a betta is potentially stressed.

The stress may develop a toll on your betta’s mental and physical health. Take immediate action for such kind of flaring.

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