Why Are My Fish At The Top Of The Tank? Reasons & Solutions

Do you observe your fish at the top of the tank, raising concerns? It could be a sign that something is wrong with your water. But, before you abandon the ship and get rid of all your fish, you should try to identify the problem first.

Fish swim at the top because they can’t get enough oxygen in the water – this is one of the most common reasons why they behave that way. Also, if there’s not enough space or enrichment in their environment, they may swim at the top to explore and find other areas they can inhabit.

Luckily, there are plenty of solutions to this problem and I’m ready to guide you through them! In this article, I’ll go over why your fish are at the top of your tank and what you can do to fix it.

Why Are My Fish At The Top Of The Tank

Why Is My Fish Staying At The Top Of The Tank?

If your fish is staying at the top of the tank instead of swimming around, it may be because they are trying to breathe more easily. Poor water quality can result in different imbalances in your tank which makes the water unsuitable for oxygen absorption. To find out what parameters need to be adjusted so that your fish can get enough oxygen, you’ll have to do some investigating and troubleshooting.

Your fish could also be ill or have a parasite infestation. Dirty water and poor conditions can lead to bacterial gill diseases or parasites like flukes that can interfere with a fish’s ability to breathe. If changing your aquarium’s water quality doesn’t improve things, it’s best to consult with a veterinarian right away to rule out any health issues.

Normal Reasons Why Fish Stay At The Top Of The Tank

Don’t worry, there could be perfectly normal explanations for this behavior. Fish can be an eccentric and captivating species with their own individualized personalities and behaviors.

Before worrying about the health of your fish, contemplate other rationalities first. Thankfully, there are many typical presumptions as to why your fish may be lingering in the uppermost part of your tank which you don’t need to be concerned about.

Some potential causes may include simply wanting more oxygen or coming closer to the surface because they enjoy being able to observe what is happening around them better from above. Additionally, if the water temperature is lower at the bottom of the tank then swimming up might also help them stay warm or like a change of scenery from time to time.


Many fish sleep near the top of the tank for safety and comfort. This is especially true for labyrinth fish like Bettas and Gouramis, who need access to oxygen that is found at the water’s surface.

Providing decorations or floating plants in a tank with these types of fish is recommended to help them settle in. If your fish floats near the top of the tank with its eyes closed, it is likely in a resting state.

Sleeping at the surface provides these fishes with a feeling of safety and protection while they rest. So, if you see your fish sleeping at the top of your tank, don’t worry – it’s just taking a break!

Feeding Time

Feeding time is one of the most common reasons why fish are found at the top of the tank. If you add food to the water, your fish will race towards it and usually stay near the surface in anticipation of the next feeding.

Even if you haven’t just added food to your tank, your fish may still find their way to the top. This could be because they smell food or they are expecting a meal before their usual feeding time. In any case, it’s normal behavior for fish and nothing to be concerned about!


Exploring is normal and healthy behavior for fish that are new to their tank. When you introduce a new fish, it will likely spend long periods of the day swimming around and getting used to its environment. This is nothing to be concerned about; in fact, it’s actually a good sign that your fish is comfortable with its new home!

By spending time at the top of the tank, your fish can explore its surroundings and take in all the sights. This type of exploration helps keep them stimulated and encourages healthy brain development. So if you see your fish spending more time than usual at the top of the tank, don’t worry — they’re just having fun exploring!

Reacting To A Change In The Tank

It’s totally normal for fish to swim to the top of the tank when they sense a change in their environment. Whether it be as small as a temperature change, or as big as a complete power outage, your fish will want to investigate and make sure everything is alright.

They may also be reacting to more minor changes that you’ve made, such as adding decorations or plants. When something new has been introduced into the tank, your fish may swim to the top to take a look around and figure out what’s going on.

If your fish only spends a few minutes at the top before returning back to its usual spot, then there’s most likely nothing wrong with it or its environment. However, if it stays at the top for long periods of time or shows other signs of distress, then it could be time for you to assess whether there is something actually amiss.

How do fish breathe?

Fish breathe differently from other animals, relying on their gills to absorb dissolved oxygen from the water. They don’t actually inhale the oxygen but instead let it diffuse through their thin gill membranes. This process works best when the oxygen levels are high and the water is moving, which is why you may see your fish lingering near areas with bubbles or where air and water mix at the surface.

The increased interaction between air and water often means that more dissolved oxygen is available in these areas, giving your fish a better chance to take in what it needs for its respiration.

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What Does it Mean When Fish Swim at the Top of the Aquarium?

If you ever find your fish swimming at the top of the aquarium, it could mean one of two things; either there’s a problem with the gills or an injury, or there’s something wrong with the water or aquarium conditions.

However, keep an eye out for multiple fish gasping at the surface – this is usually a sign that something’s off about the tank environment and needs investigation. Solve this by checking for any changes in temperature, PH levels, and other factors which may have recently altered the health of your fish tank.

Check it out – let’s explore some possibilities why your fish is taking a lap at the top!

Declining Water Quality

If you’ve noticed that your fish are swimming to the top of the aquarium, this could be due to water quality issues. Declining water quality can lead to a lack of oxygen for your fish, making it difficult for them to breathe. This is often caused by high levels of ammonia and nitrites in the aquarium, which make it difficult for your fish to take in oxygen from the water.

To check, you should do an immediate 50% water change and top up your aquarium with filtered water. You should also check for any filter-related problems as well as test the water for ammonia and nitrite levels. Other causes could include overfeeding or the presence of dead fish, both of which can pollute the aquarium environment and reduce oxygen levels too.

Water Parameters

It’s important to pay attention to the water parameters in your aquarium when trying to figure out why your fish might be swimming at the top of the tank. Poor water quality is a possible reason, and this can be caused by ammonia or nitrites present in the water.

To check if ammonia or nitrites are indeed the culprits, using a test kit or a Seneye monitoring device is recommended. If either of these substances is present, steps should be taken to reduce levels. That may include performing a non-chlorinated water change, adding API Quick Start into the water and filter, or revisiting tank cycling procedures.

No matter which approach you take, it’s vital that you identify why ammonia and/or nitrites were present in the first place so that further problems don’t arise down the road.


Once you’ve identified the cause of why your fish are swimming at the top of the tank, it’s time to take action. The first step is to perform a 50% water change and top up with filtered water. This will help reduce any ammonia or nitrite levels that may be present in the aquarium.

Not Enough Oxygen

If you find your fish swimming to the top of the tank, it can be an indication that there is a lack of oxygen in the water. Because oxygen rises in water, your fish will swim towards the top in an attempt to acquire more.

This behavior is often seen when other factors are contributing to oxygen deficiency such as still water, temperature fluctuations, and overcrowding. If any of these conditions occur within the aquarium, you should check it thoroughly and make any necessary adjustments to ensure optimal levels of oxygen in the aquarium.


If the oxygen levels in the tank are low, aerating the water can provide additional oxygen for your fish.

Move The Filter Current

Changing your tank’s current filter should be the first solution to consider. Directing the filter such that it disrupts the water surface more increases oxygen levels in the tank, resulting in swift benefits.

Exercise caution when introducing currents in a tank with fish, as it may lead to distress.

Try An Air Bubbler

Installing an air bubbler is one of the simplest options to boost oxygen levels in your tank. It’s usually cost-effective and easy to install, plus you can find decorations to hide them in order to preserve the aesthetic of the tank. Air bubblers can provide additional oxygen to the water, but they are generally not required and do not present an issue.

Add Live Plants To The Tank

Adding plants to the tank is a viable option, as they contribute to the oxygen levels while eliminating carbon dioxide.

For aquariums, Anubias nana, java moss, java fern, and marimo moss balls are all good options if you’re undecided on what plants to add. For a bolder look, hornwort and anacharis are great for oxygenation.

The Ammonia Levels Are Too High

If you’ve been noticing fish staying at the top of your tank, it can be a sign that the ammonia levels are too high. Though it looks clean and inviting, ammonia, nitrites, and nitrates could be dangerously high in the water. High levels of ammonia are hazardous to all fish in the tank and increase their risk for ammonia poisoning.

Due to the elevated levels of ammonia, various signs can appear in your fish such as gasping for air, pale gills, red streaks along their bodies and fins, inflamed eyes and anus, loss of appetite, and lethargy. By monitoring your fish’s behavior interacting with their environment then you can gain a better idea as to whether or not your tank is up to standard.


If you find yourself with ammonia levels that are too high in your fish tank, then it’s time to take action.

The first step is to make sure the water is tested, and that the Ammonia level is at 0ppm, the nitrite level is at 0ppm, and the nitrate levels are below 20ppm. An API Master Test Kit can help here: it’ll give you accurate readings for all four of these vital measurements.

Once you know what needs to be done to get your levels back down, there are simple solutions available. Making sure any uneaten food is cleared from the tank floor regularly is a good place to start, as this will keep those ammonia levels low.

You may also need to perform a partial water change if things don’t improve quickly enough – but do so gradually over several days rather than all at once. Lastly, adding oxygenating stones into your tank can help too – though always check instructions before introducing them into your tank water.

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Perform A Water Change

It is recommended to perform a water change when the levels of ammonia, nitrite, or nitrate are excessive.

In extreme cases, a 50% water change may be recommended to reduce ammonia levels by partially replacing the old water with fresh water.

Add An Ammonia Neutralizer

If the ammonia levels are not reduced sufficiently with a water change, an ammonia neutralizer may need to be added. API Ammo Lock is suggested, but any suitable product should work.

Add Ammonia Removal Media To Your Filter

Adding ammonia removal media in the filter provides additional filtration, reducing the amount of ammonia in the tank.

Aquaclear Ammonia Removers are suitable options for removing ammonia from fish tanks.

Swim Bladder

Swim Bladder is a common disease in fish that can affect the equilibrium of the fish, making it float to the top or bottom of the aquarium, swim sideways, upside down, or even stay floating at an angle. Constipation is often the biggest cause of this condition and sometimes overfeeding can lead to it as well. These symptoms might appear directly after a fish has eaten and then disappear within a few hours. For treating Swim Bladder, dietary adjustments such as providing green peas, oranges, or melon can help to prevent constipation.

This should help reduce any risk of the bladder further affecting your fish’s equilibrium. If you notice any signs that could suggest this issue in your aquatic friends, make sure to take these steps right away and keep track of their overall health!

The Tank Is Overcrowded

Having too many fish in a single tank can be a recipe for disaster. Firstly, an overcrowded tank can become dirty quickly, causing water quality to drop dramatically. Not to mention that it can also put too much stress on the oxygen levels of the water, putting your fish at risk.

Additionally, overcrowding can lead to bullying within the tank – some of your fish may feel threatened and could attempt to swim away from the other fish in an effort to find safety. This could be dangerous as they may end up trapped or struggling for oxygen near the top or bottom of the tank.

In short, if you have too many fish in one tank you will run into problems – maintain careful stock control over your aquarium and make sure your fish are all happy and healthy!


If your tank is overcrowded, there are solutions available. Relocating fish to a separate tank is ideal but not an option for everyone. If this can’t be done, other steps should be taken. These include:

Remove Bullies

If a fish is seen to remain stationary at the top of a tank in which there are other fish, it may be due to bullying from either larger, more aggressive ones, or smaller ones such as neon tetras that nip at its fins.

To manage this situation, the most suitable solution is to transfer the bullies from your tank, either by gifting them to a friend or setting up a new tank for them.

Add More Plants

Increasing the number of plants can reduce the chance of fish aggression, as it will create more hiding spots, and break up horizontal lines of sight. Plants also have the added benefit of improving water quality, by decreasing ammonia and increasing oxygen levels.

Hiding Spots

In order to provide a betta fish with necessary places of refuge, decorations such as driftwood, stones, and ornaments should be incorporated into the tank alongside plants.

The Water Temperature

The water temperature of your fish tank is incredibly important for the health and well-being of your fish. Extreme temperatures can cause fish to position themselves near the surface of the tank and increase their stress levels.

Warm water rises while cold water sinks, so if the lower parts of the tank are colder than usual, then this will mean that your fish will always try to stay in the warm part of the tank, which can be dangerous for them. On the other hand, if the temperature is too hot then this can also cause stress and other issues for your fish.

Therefore, it’s very important to monitor the temperature in your fish tank and make sure that it is at an optimal level in order to keep your beloved pets happy and healthy.


To address the issue of temperature inconsistency in a tank, there are several solutions available.

Move The Heater

The heater may not be evenly distributing heat throughout the tank, so it can be beneficial to relocate it in order to ensure even heating throughout.

Place A Heater Behind The Filter

Placing a heater behind the filter allows warm water to circulate in the tank, maintaining a higher temperature.

Associative Learning in Fish

Some fish may be able to learn and remember the time when they are usually fed, and they may come to the surface in anticipation of food when they recognize your presence in the room.

The fish may move towards the surface or side of the aquarium when it’s time for feeding, especially if you have a consistent feeding pattern.

Fish that Breathe at the Top of the Aquarium

If you have fish in your aquarium, you should know that some varieties of fish take in oxygen from the surface. Bettas, Gouramis, and other types swim to the top of the water to inhale air rather than relying on gills underwater. Before introducing any new species into an aquarium, it is essential to perform thorough research to determine if these types of fish are included.

It is important not to panic when you catch your fish swimming to the top of their tank as this could simply be their natural behavior. No alterations are necessary when maintaining different species of fish that inhabit the top of the aquarium.

Diseases That Cause Fish To Stay At The Top Of The Tank

Certain diseases and infections can cause a fish to remain at the surface of the tank, as swimming around can be difficult for them due to their weakened condition.

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These are some of the popular ones:

Aeromonas hydrophila

Aeromonas hydrophila is a bacteria that can affect fish, which is why it’s important to keep aquariums clean and free from contamination. This bacteria can cause various symptoms in fish including lethargy, loss of appetite, and difficulty swimming. These symptoms often show up after getting new fish or plants for the tank.

In order to prevent harm to your fish due to Aeromonas hydrophila, proper tank maintenance is key. If you suspect that your fish may be infected with this bacteria, consult a vet who specializes in treating fish as soon as possible. Left untreated, Aeromonas hydrophila can result in death.


Columnaris is an all-too-common bacterial infection that affects the skin and fins of fish, and it typically comes from dirty or contaminated water. White patches on the body and difficulty in movement may indicate columnaris in fish.

The symptoms of columnaris can vary from inflammation to ulcers and fin rot, which can ultimately lead to death if left untreated. Knowing what this disease looks like can save the lives of your fish, so if you see your pet fish exhibiting any of these symptoms, be sure to get them checked out right away.


Flukes are parasites that can plague a fish tank and make life difficult for your aquatic inhabitants. These nasty parasites can infest the skin, gills, and fins of your fish, making it hard for them to breathe and even leading to the fish staying at the top of the tank. They’re usually introduced through new fish or plants that come into the tank.

If you happen to notice that your fish are scratching themselves more than usual, have clouded eyes, losing weight, or having breathing difficulties, then they could easily be suffering from flukes. Left untreated, this issue can quickly lead to death so it’s important to bring them to a vet immediately if you suspect flukes. If caught early enough though, you may be able to save your beloved fish!


Ich is a parasitic infection that can be very dangerous for your fish. It results in white spots appearing on their bodies and can also lead to listlessness, difficulty swimming, and respiratory complications. What’s more, Ich is highly contagious which is why it’s critical that you act quickly if you notice the first signs of this disease.

The best way to protect other fish in your tank from catching Ich is to move the affected ones into a quarantine or hospital tank and give them the necessary medication. This should stop the spread of the disease while also easing any symptoms your fish may be experiencing. If caught early enough, most cases of Ich can be successfully treated.

Swim bladder disorder

Swim bladder disorder is a condition that affects the swim bladder, an organ that helps fish stay buoyant. It can be caused by various factors, like infection, tumors, constipation, genetics, or environmental issues such as changes in water temperature, poor water quality, and bad water parameters.

Fish with swim bladder disorder typically show signs of difficulty swimming or being inverted. You will also spot strange swimming movements such as body wiggling from side to side. In case you witness any of these symptoms in your fish tank – you should inspect if they have swim bladder disorder.

Preventing Issues That Cause Fish To Stay At The Top Of The Tank

Owning a tank full of healthy, happy fish is certainly possible as long as you take the time to create the best environment for them. To prevent your fish from staying at the top of the tank, consider taking some preventative measures.

The most important step is to regularly change out your aquarium water. Implementing this approach will promote water quality and reduce the potential accumulation of hazardous toxins.

Follow up with regular aquarium maintenance to thoroughly clean both the tank and its filters while removing any dead plants or fish that have accumulated in the tank over time.

Whenever introducing new fish into your aquarium, be sure to quarantine them first before releasing them into their new home. By doing this, you’ll be able to help avoid spreading potential disease or infection among other fishes already living in your tank.

Finally, ensure that all essential levels such as temperature, ammonia, and nitrite levels; oxygen levels are kept regulated for a healthy environment for your little underwater buddies! Keep an eye on their habits and overall environment so if something has changed – prompt action can be taken accordingly.

Other factors worth mentioning

When it comes to keeping your fish happy and healthy, there are a few other factors worth mentioning. Low lighting, loud noises, new fish bullying old fish, and disease can all cause problems for your fish.

Low lighting can be too much of a strain on some varieties of fish while loud noises, such as the sound from the filter, can startle them and make them skittish. Feeding your fish regularly is also important – if they’re not getting enough food they may come to the surface waiting to be fed.

Finally, overcrowding or disease can also be responsible for pushing some fish to the surface. Bloated bodies, extra mucous production, open wounds, or burns are signs of a possible disease so keep an eye out for any changes in your tank.


It can be stressful worrying about why your fish are at the top of their tank. However, with a little bit of understanding and care, you can keep your fish happy, healthy, and swimming throughout their entire aquarium.

Remember to look out for any signs of distress, provide them with the best water quality possible and watch for any changes in behavior. The most important thing is to remain vigilant so you can respond immediately if needed.


Having fish that stay at the top of the tank? Discover why & what you can do to make them more comfortable. Clear answers & tips here.