Why Is My Betta Fish Obsessed With Filter?

Why Is My Betta Fish Obsessed With Filter

It is not uncommon to see your betta hanging around near the filter. I have seen many bettas obsessed with the filter. Either they try to swim against the current or just hang around near the outlet of the filter. Why bettas are obsessed with filter?

Bettas prefer the area near the filter outlet because it has a good flow rate. This area has more oxygen due to the good flow rate, compared to other parts of the tank. The higher oxygen level in this area makes breathing easier for the betta.

Bettas also like to swim against moderate current. This is one kind of entertainment for them. However, if the betta struggles to swim straight, that means the current is too strong for him and you need to do something immediately.

Key Takeaways

  • Bettas are drawn to the higher oxygen levels near the filter.
  • The filter’s water flow provides stimulation and mimics their natural environment.
  • Bettas’ natural instincts for exploration and hunting are triggered by the filter’s movement and vibrations.
  • Male bettas might perceive the filter as a threat to their bubble nests.
  • The area around the filter can serve as a hiding place, offering a sense of security.
  • Bettas enjoy swimming against the gentle current created by the filter.
  • The filter area might be quieter and less stressful for the betta.
my betta fish tank front view horizontal

Why Is My Betta Fish Obsessed With Filter?

It’s not uncommon for betta fish to show interest in or even become fixated on their aquarium filter. There could be a few reasons for this behavior:

Water flow stimulation:

Betta fish are naturally curious and active. The movement of water created by the filter can simulate their natural environment, where they encounter currents and flowing water in the wild. This stimulation might intrigue them and keep them engaged.

Betta fish are drawn to filters due to water flow stimulation, mimicking their natural environment.

Exploration and hunting instincts:

Betta fish are known to be territorial and have a natural instinct to explore their surroundings. The filter’s movement and the vibrations it creates can mimic prey or potential hiding places, triggering their hunting instincts.

The movement and vibrations from filters trigger their exploration and hunting instincts.

Bubble nest preparation:

Male bettas build bubble nests, which are structures made of bubbles on the water’s surface, as a part of their reproductive behavior. The filter’s movement might make them perceive it as a potential threat to their bubble nest, leading them to investigate and defend their territory.

If your betta fish seems excessively fixated on the filter to the point of stress or exhaustion, it’s important to ensure that the filter’s flow isn’t too strong for your fish.

Strong currents can stress bettas and make it difficult for them to swim comfortably. Consider adjusting the flow or adding filter baffles to reduce the water movement.

Providing plenty of hiding places and enrichment in the tank, such as plants, caves, or decorations, can also help divert their attention from the filter.

Betta fish do benefit from having a filter in their tank. Filters help maintain healthy water parameters by removing waste and keeping nitrate and ammonia levels low. This is important for betta health and longevity.

Hiding Place

Betta fish, like many other fish species, naturally seek out hiding places. This behavior is rooted in their instinct to protect themselves from predators.

The area around the filter, especially if it has plants or decorations nearby, can provide a sense of security and a place to retreat. Bettas enjoy having their own space where they feel safe, and the filter area might just be their preferred spot.

Swimming Against The Current

Bettas are known to enjoy a gentle current, even though they generally prefer still water. The filter often creates a mild current in its vicinity.

Your betta might be enjoying the sensation of swimming against this current. This activity is not only stimulating for them but also provides good exercise, helping to keep them healthy and fit.

Quiet Place

Despite their reputation for being hardy, betta fish are sensitive to their environment and can get stressed by too much noise or activity.

The filter area might be the quietest part of the tank, offering a respite from any disturbances. This spot could be providing your betta with a peaceful zone where they can relax away from the more active areas of the aquarium.

Male bettas perceive filters as threats to their bubble nests, leading them to investigate.

Owner: Shea Willis

In an interview with Mary McCauley, owner of the Arizona-based betta fish rescue center Mary’s Magic Bettas, she stressed the importance of including a gentle filter in an ideal betta habitat.

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“While bettas can surface breathe, they also need oxygenated water which is best achieved with a filter,” McCauley said.

She recommended sponge filters as the gentlest option, which provide filtration without excess water flow that could stress long-finned betta fish.

Is The Betta Struggling To Swim Near The Filter?

Look closely when the betta is swimming against the current of the filter outlet. Is it swimming straight? Is there any sign of struggle?

If you see the betta is struggling, then it is an indication that the filter flow rate is too strong. You need to reduce it immediately. That is not a problem with most modern filters as they come with an adjustment knob.

Just adjust the knob to your desired flow rate. However, if your filter doesn’t have an adjustment knob then what to do? Well, the best option will be to buy a better filter with adjustment knob.

But, if you don’t have the budget, there are some things you can do to tone down the flow rate significantly.

In the next section, I’ll talk about some of the DIY ways to reduce the filter flow rate.


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Reducing The Filter Flow Rate

Before discussing some of the DIY ways to reduce the filter flow rate, let me start by saying that the best way to reduce the flow rate is by using the adjustment knob. Most filters these days come with an adjustment knob.

If your filter doesn’t, chances are it is not a very good quality product and you might need to upgrade your filtration system.

With that being said, let’s look at some of the DIY ways to reduce the filter flow rate:

Use Pre-filter sponge

The first thing you can do is use a sponge on the inlet of the filter. Inlet is the opening of the filter inside the aquarium through which water enters the filter. If you can reduce the rate of water entering the filter, then it will automatically reduce the filter flow rate.

If you don’t have any sponge lying around, just take a piece of filter floss, cut it into a small rectangle and wrap it around the inlet. It will also act as a fantastic mechanical filtration.

Stuff Filter Floss Inside

If the filter flow rate is still too much, stuff some filter floss inside the filter chamber. Most HOBs have a divider inside their chamber. The divider divides the chamber into two compartments.

Water gets collected into the first chamber and then enters the second chamber through some kind of hole or notch at the top. At the second chamber, there are all types of filter media.

You can put some filter floss over the hole or notch through which water enters the second chamber from the first chamber. This second piece of filter floss will also create some kind of barrier in the water’s path and reduce the filter flow rate.

Create A Baffle

This is the best DIY method to reduce filter flow rate. However, it needs some working. You’ll need to have a plastic bottle first.

Cut the top and bottom of the bottle with a sharp scissor, also make sure the bottle length matches the length of the filter outlet.

Now, cut the bottle lengthwise so that it is no longer a tube. After that, you’ll need to attach the bottle to the filter outlet so that water first hits the side of the bottle and then falls down. The process is much easier to show than explain. If you are confused, just watch the above video.

This method will significantly reduce the filter flow rate. However, it doesn’t look good and may need frequent maintenance.

If you ask me, I’ll always recommend to buy a good filter that comes with adjustable flow rate options.

Why Does My Betta Fish Stay By The Filter?

You might hear of the playful temperament of betta fish. So, you must be surprised to discover your betta staying by the filter.

Many betta owners ask- why does my betta stay by the tank? Let’s check out the probable answers to this curiosity.

1. Presence Of More Oxygen

The prime purpose of a filtration system is to purify the water. While purifying the water, a filter increases its flow rate, which causes more oxygenation in the surrounding filter area.

If the oxygen level is low in the betta tank, your betta will seek adequate oxygen. Since there is more oxygen in the filter area, your betta will want to stay by the filter.

2. High Water Flow

If the current of your filter is too strong, your betta will try to avoid it. Due to the high water flow, your betta fish may find swimming against the water current difficult.

For this reason, your betta wants a comfortable place where the water current may seem non-existent. That’s why, your betta fish may stay beside the filter to avoid high water currents.

Owner: Ok_Zone2813

3. Feeling Secured

If you do not add sufficient hideouts in the tank, your betta may not find a suitable space to hide. Sometimes, betta requires some secure place to take a rest.

That’s why the experts suggest adding adequate plants, décor items, caves, etc. Your betta may want to feel secure by staying beside the filter since it works as a place to hide.

4. The Water Near The Bottom Isn’t Clean

Your betta fish will choose to stay by the filter if the tank bottom isn’t clean. There might be an assembly of decaying matters, leftovers, and so on. It causes poor water conditions in your betta tank.

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Although betta roams all over the aquarium, poor water condition makes them choose the cleanest water area. No wonder that filter area is preferable for betta due to drawing water by the filter.

5. Catching Preys Easily

You might know that betta fish are opportunistic feeders. The current of the filter makes small fish inclined to the filtration system. So, the filter area becomes a good source of food for your betta. When betta hides beside the filter, it’ll help them catch prey readily.

6. Escaping From Aggressive Tank Mates

If you keep your betta with territorial tank mates, your betta may not swim freely. It’ll try to escape from the bullies. The bully and aggression of tank mates may make your betta stressed.

That’s why your betta looks for a secure place to hide from their aggressive tank mates. If your betta tank lacks adequate hideouts, your betta will stay by the filter.

7. Breeding Period

If your betta fish are breeding, you should provide them with proper privacy. To assure safety, you should add lots of hiding spaces. In case, your betta does not feel safe in their breeding period,

8. Overcrowded Tank

If your betta fish stay by the filter, you should check the condition of the tank. Overcrowding may cause your betta fish to look for a comfortable corner.

9. Boredom

Lastly, there might not be any specific reasons for your betta fish to stay by the filter. Sometimes, betta tends to stay beside the filter due to boredom or laziness. Since the water flow is low in the filter area, your betta.

Owner: Samantha Christy

Why Is My Betta Fish Hiding Behind The Filter?

Hiding behind the filter can be a serious sign of something wrong in your betta tank. If your betta fish hides behind the filter, you should check for the potential reason.

Although betta fish are hardy, these fish get stressed over fluctuations in environmental parameters. Sometimes, there can be changes in temperature, pH, and other water parameters. If the water current is too strong, it can make your betta stressed.

These environmental malfunctions make your betta look for a secure place. If your betta tank does not have sufficient hideouts, your betta may hide behind the filter.

The further reason can be feeling threatened or insecure. Your betta may get bullied by its aggressive tank mates.

Sometimes, the bright light of the room can make your betta puzzled. To get rid of uneasiness, these bettas may find a good corner to hide behind the filter.

In addition, you should check the health of your betta if your pet betta is hiding behind the filter. Your betta may be hurt by any sharp edge or tank mates. Besides, illness can cause your betta stressed which makes them hide behind the filter.

However, there might be nothing wrong in the tank environment when your betta acts weirdly. It can happen when you introduce your betta new. Before getting accustomed to the tank environment, your betta may hide behind the filter.

If overly fixated, it’s crucial to check if the filter’s flow is too strong for your fish.

my betta fish tank front view

Why is my betta fish laying on side?

If your betta fish is lying on its side, it could be an indication of a health problem. There are several potential causes for this behavior:

Swim bladder disorder: One common issue that can cause a betta fish to lie on its side is swim bladder disorder. The swim bladder is an organ that helps fish control their buoyancy. If it becomes inflamed or infected, it can affect the fish’s ability to swim properly, causing them to float or sink and rest on their side.

Poor water conditions: Betta fish are sensitive to water quality, and poor water conditions can lead to various health issues. High levels of ammonia, nitrites, or nitrates in the water can cause stress and negatively impact the fish’s health, potentially leading to abnormal swimming behavior.

Infections or diseases: Bacterial or fungal infections, parasites, and other diseases can affect a betta fish’s balance and behavior. These conditions may cause the fish to become lethargic, lose its equilibrium, and rest on its side.

Injury or physical trauma: If your betta fish has experienced an injury or physical trauma, such as bumping into tank decorations or fighting with other fish, it may result in difficulty swimming and lying on its side.

Why is my betta fish staying at top of tank?

If your betta fish is consistently staying at the top of the tank, there could be a few reasons for this behavior:

Oxygen deficiency: Betta fish require oxygen to breathe, and if the oxygen levels in the water are low, they may swim to the top of the tank where the water and air interface to access more oxygen. This behavior can indicate inadequate aeration or poor water circulation, especially if your tank lacks a proper air pump or filter.

Water temperature: Bettas are tropical fish that thrive in warm water conditions. If the water temperature is too low, they may seek warmer areas near the water surface where the temperature is slightly higher.

Stress or discomfort: Stressors such as aggressive tankmates, excessive noise, sudden changes in water parameters, or inappropriate tank conditions can make betta fish feel uneasy. They may try to escape or find refuge at the top of the tank as a response to stress.

Feeding anticipation: Betta fish often associate the top of the tank with feeding time. If your fish has learned that you feed them from the top, they may eagerly wait there in anticipation of food.

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Why is my betta hiding in a corner?

There are several reasons why a betta fish may hide in a corner of the tank. Some possible reasons include not having enough hiding spaces or plants, feeling stressed or uncomfortable due to water quality issues, experiencing ammonia poisoning, or being sick or injured.

my betta tank top view

Betta fish got stuck to filter, what to do?

If your betta fish has gotten stuck to the filter, it’s important to act quickly to ensure their safety. Here are the steps you can take:

1. Turn off the filter: Immediately switch off the filter to stop the water flow and prevent any further harm to your betta.

2. Gently remove the betta: Carefully and gently free your betta fish from the filter. If it’s stuck, try to loosen any fins or body parts that may be caught without causing any additional harm. Be patient and avoid pulling forcefully.

3. Assess the fish’s condition: Once the betta fish is free, observe it closely for any visible injuries or signs of distress. Look for torn fins, abrasions, or any difficulty in swimming. If you notice any significant injuries or if the fish appears to be struggling, consider seeking veterinary assistance.

4. Provide a stress-free environment: After the incident, it’s crucial to provide a calm and stress-free environment for your betta. Ensure that the water quality is optimal, the temperature is appropriate, and the tank has hiding spots or plants where your betta can retreat.

5. Monitor and care for your betta: Keep a close eye on your betta fish in the following days. Watch for any signs of stress, illness, or behavioral changes. Maintain a regular feeding schedule and ensure that the tank conditions remain suitable for your betta’s well-being.

If you have any concerns about your betta fish’s health or well-being, it’s always best to consult a veterinarian with experience in fish care for further guidance and assistance.

Why does my betta fish sleep by the filter?

Betta fish may sleep by the filter for a variety of reasons. One possible reason is that the filter creates a gentle flow of water that the betta fish finds soothing and comfortable. Additionally, the filter may provide a more oxygen-rich spot for the betta fish to sleep in. 

Can a filter kill a betta fish?


A filter can harm or even kill a betta fish if certain precautions aren’t taken. While filters are designed to maintain water quality by removing toxins and impurities, they can create strong currents that are overwhelming for betta fish.

If the filter creates a strong current, it can stress out the betta fish and even cause physical harm.

To prevent harm to the betta fish, it is recommended to choose a filter with adjustable flow or baffle the output with a sponge to reduce the current.

Overall, it is important to ensure that the filter is appropriate for the tank size and that the betta fish is not being harmed by the filter’s output.

Adjusting the flow or adding filter baffles can help, as can providing enrichment like plants or caves to divert their attention

Why is my betta fish staying by the heater?

Betta fish are known to be tropical fish that prefer warm water temperatures. If your betta fish is staying by the heater, it may be seeking out the warmth it provides. Here are a few possible reasons for this behavior:

Temperature preference: Betta fish thrive in water temperatures between 78°F and 80°F (25.5°C to 26.5°C). If the water temperature in your aquarium is lower than their ideal range, the betta may naturally gravitate towards the heater to warm up. The heater provides a consistent source of heat, creating a comfortable environment for the betta.

Thermoregulation: Like all fish, bettas need to maintain their body temperature within a specific range for optimal physiological functioning. By staying close to the heater, your betta can regulate its body temperature more effectively. It can move closer to the heater when it feels too cool and move away when it feels too warm, ensuring it stays within its comfort zone.

Seeking comfort and security: Bettas are known to be solitary and territorial fish. They often establish their territory and may feel more secure and comfortable when near a heat source. The heater could provide a sense of security and familiarity, making the betta more likely to stay in its vicinity.

Why does my betta fish stay at the bottom of the tank?

One of the most common reasons is that the betta fish is resting or sleeping. However, if the betta fish is staying at the bottom for an extended period of time, it could be a sign of stress, illness, or poor water quality.

Why does my betta fish swim away from me?


The betta fish might be naturally shy or timid, and may feel threatened by human presence. The betta might also be stressed or uncomfortable due to poor water quality or inadequate tank conditions.

Additionally, if the betta fish is new to the tank or has not yet bonded with its owner, it may be more likely to swim away from humans.

Do Bettas Like Water Current?

The answer is no! Bettas can not thrive well when there is a strong water current.

Since betta isn’t a good swimmer, these tropical fish can’t withstand strong currents. Your betta will become stressed soon due to swimming against a strong current. Because of fatigue, your betta may face injuries also.

If your betta swims at an angle, the current may push it away. In addition, you may notice your betta swimming uncomfortably. It may cause your betta to hide and avoid the current.

Muntaseer Rahman

About Author

Hello, I’m Muntaseer Rahman, the owner of AcuarioPets.com. I’m passionate about aquarium pets like shrimps, snails, crabs, and crayfish. I’ve created this website to share my expertise and help you provide better care for these amazing pets.

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