14 Reasons Fish Lay At The Bottom Of The Tank

Betta ebook-ban

Last Updated on 2023-10-28

If your fish is laying at the bottom of the tank, then of course you’re going to be concerned, and possibly with good reason. If you want to know why your fish is laying at the bottom of the tank, and more importantly, what you can do about it, then keep reading to find out!

And most importantly, if you still have any questions after reading this article, leave them in the comment section!

Key Takeaways:

  • Fish lying at the bottom of the tank can be normal behavior for some species, like bettas, who sleep or rest at the tank bottom.
  • Reasons for fish lying at the bottom range from simple behaviors like relaxation or being bottom-dwelling species to more concerning issues like stress, territorial behavior, or illness.
  • Observing fish behavior and knowing their normal routine is crucial to detect any concerning changes in behavior.
  • Causes for concern include overcrowded tanks, lack of hiding spots, stress factors, incompatible tank mates, poor water quality, and illness.
  • Recommended actions involve monitoring and maintaining suitable tank conditions, testing water quality, providing hiding spots, and considering fish compatibility and appropriate tank size.

Is It Normal For Fish To Lay At The Bottom Of The Tank?

When fish lay at the bottom of their tanks or aquariums, then of course, it’s perfectly normal to panic, However, there are some instances where this is completely normal behavior. Of course, there are also occasions where laying at the bottom of the tank is a symptom of your fish feeling sick or struggling with something happening in the tank. 

When you observe your fish over time, you’ll get to know what is normal for them and what isn’t. While it may be more simple than other pets, fish do have their own personalities, so if you notice a change in their personality, then something is probably wrong.

Changes in typical behavior and routine are one such way that we can tell that our fish aren’t happy. 

How your fish behaves when lying at the bottom of their tank is another good indicator of whether or not you should be concerned that something’s wrong. If they are just simply lying down, they are likely fine. 

Why Do Fish Lay At The Bottom Of The Tank? 

Fish can be found laying at the bottom of the tank for a number of reasons. Some of these reasons are either completely innocent or are part of a fish’s normal behavior, and there are simple solutions to fix the issue. 

There are also ways to tell if you need to keep a closer eye on your fish in case they’re unwell. If there’s the potential that a serious problem or a sickness is causing this change in behavior, your fish is going to do the best they can to communicate this to you through other signs and symptoms. 

Here are all the reasons that your fish may be laying at the bottom of their tank.

Concern/ReasonDescriptionAction to Take
SleepingFish like bettas sleep at the bottom.Turn off lights at intervals.
RelaxingFish may float near the bottom to relax.Observe breathing and pelvic fins.
Bottom DwellerSome fish naturally stay close to the bottom.No action needed.
New EnvironmentNew fish may stay at the bottom initially.Give them time to adjust.
Lack of SpaceOvercrowded tanks can stress fish.Upgrade the tank or optimize layout.
BoredomLack of stimulation can be an issue.Add plants, decorations, and toys.
StressVarious factors can stress fish.Check water quality and tank mates.
TerritoryFish might fight over territory.Create more hideouts and consider dividers.
HidingFish may hide if bullied.Add more hiding spots and check compatibility.
Wrong TemperatureSudden changes can stress fish.Monitor and adjust temperature.
Strong CurrentSome fish prefer calm water.Adjust water current.
Poor Water QualityHarmful substances can make fish sick.Monitor water quality.
SicknessIllness can cause this behavior.Quarantine and treat the fish.
IchIch makes fish itchy and lay at the bottom.Treat for ich; look for white spots.
Water TemperatureRapid changes can cause shock.Adjust the heater; monitor temperature.
Water QualityPoor water quality can stress fish.Use a testing kit for ammonia, nitrites, nitrates, and pH.
Tank MatesCompatibility issues can stress fish.Research breed characteristics; separate unruly fish.
QuarantineSick fish should be isolated.Move the sick fish to a separate tank.
Hiding SpotsLack of hiding spots can stress fish.Add more plants and decorations.
Tank SizeOvercrowding is stressful for fish.Upgrade to a bigger tank or get an additional one.
Tank PlacementRoom temperature and noise can affect fish.Move the tank to a more suitable environment.
DietPoor diet can make fish lethargic.Switch to high-quality food; monitor eating habits.

Normal Reasons Your Fish Is At The Bottom Of The Tank

First of all there are plenty of normal reasons for your fish to be laying at the bottom of the tank, so before you start worrying, make sure it’s not any of the following:

Your Fish Is Sleeping 

Some fish (like bettas) occasionally sleep a the bottom of their tank, especially if there are nice soft plats to lay on. Resting at the bottom helps them stay hidden from other fish who are still awake and might disturb their peaceful slumber. 

Older fish who have less energy during the day may also prefer sleeping at the bottom of the tank. Having your fish rest and sleep is encouraged, so the lights should be turned off every day at certain intervals to support that need. 

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Your Fish Is Relaxing 

Fish need to take some time to themselves to relax, just like we do. This may include them simply lounging or floating near the bottom of the tank. You’ll be able to tell if they are just trying to relax if their breathing is regularly paced and their pelvic fins are ever-so-slightly moving. 

The easiest wayt o tell if they are just sleeping or relaxing is to agitate the water near them. If they start swimming perfectly fine then the chances are there isn’t a problem. 

Your Fish Is A Bottom Dweller 

There are some types of fish that enjoy staying close to the bottom of the tank. In the wild, they stay near the substrate where they enjoy the calmness of the bottom, being close to their plants, and staying separate from the other fish who like swimming at the top of the tank. 

Many fish who enjoy bottom-dwelling are also bottom feeders. They search for food that sinks to the bottom of the tank or nibble on crumbs that fall on your aquatic plants. 

Your Fish Is Getting Accustomed To Their New Environment 

If you’ve recently introduced a new fish to your tank, they might gravitate towards the bottom of the tank as they get used to their new surroundings. This may reign true even if they’re the only fish in the tank. It’ll likely take a couple of weeks before they feel comfortable resting in other areas of the tank. 

Reasons To Be Concerned About

While there are plenty of normal reasons for your fish to be at the bottom of the tank, there are also some you should be more concerned about, you should act quickly to fix the issue!

There Isn’t Enough Room In The Tank 

The size of your tank needs to account for each fish having space to swim, play, rest, and eat while also accounting for space to set up plants and accessories. Some fish like having more space than others do. If your tank is too crowded, some fish might lay on the bottom in an effort to get away from everybody else.

  1. Upgrade Your Tank: The easiest way to give your fish more room is to upgrade to a larger tank. This isn’t just a luxury—it’s essential for their well-being.
  2. Optimize Tank Layout: Rethink how you’ve positioned plants, rocks, and decorations. Could you arrange them to create more open spaces?
  3. Fish Relocation: If a bigger tank isn’t an option, consider giving some fish to friends or returning them to the store. Make sure the remaining fish are compatible and have enough room to move around.
  4. Cap Fish Numbers: Going forward, resist the temptation to buy more fish than your tank can realistically accommodate. It might be tempting when you see that colorful new breed, but remember: a happier fish is one with more room to roam.

Your Fish Is Bored 

Fish need stimulation, just like any other animal. Some fish even like to play. If there isn’t enough opportunity for play and activity in your fish’s tank, they might get bored and just lazily lay at the bottom of the tank. 

There should be a combination of aquatic plants and decorations in their tank that your fish can lay on, swim through, and push around. You might have to be selective based on your particular fish’s wants and needs so you cater to their preferences. 

  1. Add Plants: Adding live plants not only enhances the aesthetic appeal of your tank but also provides your fish with something to swim around and through.
  2. Decorations: Don’t forget to add caves, tunnels, or even sunken pirate ships. These offer excellent hiding and exploration spots.
  3. Toys and Accessories: Believe it or not, fish toys exist! Products like floating logs and activity rings can keep your fish busy.
  4. Rotate Decor: Every couple of weeks, consider changing the layout or swapping out decorations. This novel environment keeps your fish engaged.

Your Fish Is Stressed Out 

It cannot be overstated how bad stress is for fish. The smallest source of stress can cause your fish to behave in unusual ways, which could include them laying at the bottom of the tank. It may take some trial and error to find the root cause of their stress, but it’s necessary to get them acting normally again. 

  1. Water Quality: Test your water for the basics—pH, ammonia, nitrites, and nitrates. Poor water quality is a top stressor for fish.
  2. Temperature Fluctuations: Fish are sensitive to temperature changes. Make sure your tank’s heater is functioning properly.
  3. Incompatible Tank Mates: Not all fish get along. Make sure you don’t have any bullies or incompatible species in the tank.
  4. Overfeeding: Too much food can foul the water and cause stress. Stick to a feeding schedule and be mindful of portion sizes.
  5. Noise and Light: Believe it or not, loud noises and bright lights can stress your fish. Keep the tank environment as tranquil as possible.

Your Fish Is Trying To Establish Territory 

If you have multiple tank mates together and they seem to fight towards the bottom of the tank, they might be fighting over territory. This might happen if there aren’t enough areas for fish to hide or rest away from others. It may also happen if you’ve put fish that naturally don’t like each other in the same tank.

In my experience i’ve noticed this with plecos, however, I’m sure there are other fish that might do this as well. 

  1. Create Hideouts: Increase the number of hiding spots using caves, rocks, and plants. This gives fish their own little sanctuary, and makes them all feel safer.
  2. Dividers: If the tank layout allows it, temporary dividers can separate particularly aggressive fish until they become more accustomed to sharing space.
  3. Choose Compatible Mates: Do your research before introducing new tank mates. Compatibility is crucial.
  4. Rotate Decor: A changing environment can help reset territorial claims, making it harder for any single fish to lay permanent claim.

In my own experience, I’ve found that territorial behavior can also be mitigated by how you introduce new fish to the tank. Gradually acclimating them, sometimes even in a separate ‘introduction tank,’ can help ease social tensions.

They Are Hiding From Other Fish 

Fish may hide at the bottom of their tank between decorations or plants if other fish are pestering them. You might notice that this fish gets chased around a lot, and tends to scurry back to the bottom quickly when they try to swim up, only to get ambushed by another fish. 

Some types of fish are known to not get along with certain fish, so it’s crucial to be selective when putting together a fish tank of several different breeds of fish. 

  1. Multiple Hiding Spots: One of the best things you can do is make sure you’ve added plenty of hiding spots for more shy fish. Counterintuitively, when your fish has more places to hide, the more extraverted they’ll become.

The Wrong Water Temperature 

Many types of fish are very particular about how they like their water. Their water needs to mimic their natural environment as much as possible, and if you’re mixing types of fish, they should only be mixed if they have similar water parameter needs.

With this in mind, monitor water temperature regularly, as it doesn’t take much for the water temperature to change. Sometimes even a particularly hot or cold day are enough, ESPECIALLY if you don’t have a heater.

Fish who are stressed because of temperature change may appear to be struggling to breathe and may seem erratic. 

  1. Regular Monitoring: Make sure you’re using a thermometer so you can check the temperature in the tank at all times.
  2. Use A Heater: Make sure you’ve also invested in a heater so that you know you can keep the temperature in your tank reliably stable at all times.

The Water Current Is Too Strong

Most fish like calm water in their tank, but not all of them do. If the current manages to sway too much, no matter the reason, it can make your fish scared, and they’ll lay at the bottom of the tank to try and escape the current. Be sure you’re pairing tank mates that like the same kind of current together, so everyone is happy. 

Poor Water Quality

All sorts of nasty things can develop in tank water when it’s not cycled properly or replaced with fresh water occasionally. Some of this buildup in the water can make your fish very sick, and this type of sickness can be fatal. This could include ammonia poisoning or nitrate poisoning. 

You should have a routine in place to monitor what’s in the water to catch it before it makes your fish sick. Any deviation from this routine might cause something to fester in the water for long enough to impact your fish. 

Your Fish Is Sick 

There are some illnesses known to cause certain behaviors in fish to be aware of. One such manifestation of these illnesses is a fish’s propensity to stay at the bottom of the tank.

You’ll likely notice other signs, such as a lack of appetite, frantic gills or fins, and lethargy. A poor diet can also lead to illness, less energy, and refusal to eat. 

Some of the infections or bacterial fungi that fish can catch are contagious, while others aren’t. Often, your fish will have to be quarantined, water will need to be treated, and in some cases, the fish may need medicine. 

Your Fish Has Ich 

Ich is a contagious illness that can make fish miserable, and it can be fatal if it’s not treated. Thankfully, it is fairly easy to notice if your fish has ich, and it’s easy to treat. 

Fish tend to gravitate towards the bottom of their tanks when they have ich, and you might also notice they rub themselves against the bottom. This is because ich makes them itchy. You may also notice that fish with ich have white spots that form on their bodies. 

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What To Do If Your Fish Is Laying At The Bottom Of The Tank 

As mentioned, not all reasons for fish staying at the bottom of a tank are bad. However, if your fish is showing some concerning symptoms alongside this behavior, there are ways to take care of the potential issue at hand. If you can’t quite figure out whether or not your fish is acting irregularly, there are always ways to investigate before taking action. 

Check Water Temperature 

Water temperature always needs to be monitored as it can go up and down very easily.

When water temperature goes up or down, especially in a short amount of time, it can even cause temperature shock which can be fatal incredibly quickly. So if you notice that temperature is the problem, then you should adjust your heater accordingly.

Test The Water

Other factors in the water outside of temperature can make your fish feel sick or stressed out, which can be one reason why they are laying low in their tank. You should always have a testing kit handy to make sure that the ammonia, nitrites and nitrates aren’t high and the pH is balanced appropriately.

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Put The Right Tank Mates Together 

It’s strongly recommended you know about the breed characteristics and preferences of fish before bringing one home. Some types of fish like to be on their own, some fish don’t like other fish of the same sex, and some fish need to be in a tank with other fish to be happy. 

Knowing these preferences before you purchase fish and putting them in a tank at home can help save you and your fish a lot of stress. 

Quarantine The Fish

If you have multiple fish in one tank and you believe one of your fish could be sick, you should quarantine them to avoid having them spread their illness to the rest of their tank mates. This involves safely taking that fish out of the communal tank and placing them into a clean tank until they are healthy again. 

Separate Unruly Fish 

Mistakes happen, but if you’ve already picked unruly fish, you should separate them from the rest of the tank. This discourse can cause all fish involved stress, which is dangerous for a fish’s health. 

Add Hiding And Resting Spots To The Tank 

If your suspicion is that your fish are just resting or looking to have some space away from other fish, your tank may benefit from having some more plants or and decorations in it. This will give your fish other types of surfaces to hide in and rest on, as well as entertain themselves with. 

This can help reduce the chances of some fish pushing other fish around because they’re bored or because they are trying to reign supreme over their tank mates. 

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Get A Bigger/An Additional Tank 

While it’s lovely to watch a bunch of fish swimming around in a tank, overcrowding can be a major issue for all fish involved. Be sure your tank is big enough to suit the types of fish and the amount of fish you have at home. Otherwise, it may be time to upgrade the size or get a second tank to accommodate everyone. 

Move The Tank To A More Suitable Environment 

The placement of your fish tank in your home is important. If the room gets too warm or cool or is too noisy, your fish may get stressed out and start behaving differently. Placing an aquarium by a window may not be ideal, as it’s likely that the presence or absence of sun will lead to temperature changes in the water too frequently. 

 It could be worth moving your tank to a quieter room with more temperature control if nothing else seems to work, though you shouldn’t do this very often. You should also ensure that pets are kept away from fish tanks and that it’s not too close to a television or other source of constant noise. 

Change Their Food 

It may seem unrelated, but a fish’s diet is important to its health and happiness. Some fish can’t get by on cheap, generic fish foods, and over time, this poor quality food can lead them to become unhappy and tired, and they might just lay at the bottom of the tank. 

Be sure you know what to feed your fish based on their breed, and ensure you’re watching that they actually eat their food. A food switch could be all they need to perk up and start exploring their tank again. 

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Be Patient With New Fish 

Bringing home a new fish and transferring them to a new tank, only for them to stay at the bottom, can be worrisome. It’s not abnormal for fish to stay fairly still in a spot where they feel safe when they are trying to adapt to their new home. 

As long as the fish is eating and they aren’t being bothered by other fish, you will just have to stay patient until they get used to the tank. 

Here’s a video by Blue Aquatics on what to do if your fish is sitting at the bottom of the tank.

Frequently Asked Questions

As previously discussed, some breeds of fish like hanging out towards the bottom of the tank as part of their typical routine. Others aren’t known to do this much. It all depends on what kind of fish you have. 

Why Is My Oscar Fish Laying On Side At Bottom Of Tank?

Oscar fish, in particular, will lay on their side at the bottom of the tank when they are feeling uncomfortable or unsafe in their tank. This is somewhat common when you’ve just transferred your oscar fish to a new home, and they are trying to gather their bearings. This should hopefully be a temporary behavior. 

If you have oscar fish in a tank with other fish, be sure that they are placed with the right kinds of fish. Oscar fish are fairly docile, so if other fish are pestering or bullying them, they might lay at the bottom of the tank in an effort to surrender to the other fish. 

Why Is My Betta Fish Laying On The Bottom Of The Tank?

Bettas will sometimes sleep at the bottom of their tank, but typically speaking, they will usually lay on something. Since bettas tend to be more animated fish, if you notice a change in their activity or personality, there’s a good chance they are lying at the bottom of the tank because they aren’t feeling well. 

Some of the root causes of this change in behavior could be inadequate water conditions, the temperature of the water being off, they are feeling sick, or they are starting to slow down with age. Look for signs of lethargy or a lack of appetite to try and determine whether or not they are sick and check the quality and cleanliness of their water. 

Why Is My Molly Fish Laying On The Bottom Of The Tank?

Molly fish are one type of fish that aren’t known for liking the bottom of the tank. The only time it’s normal for molly fish, in particular, is when they are sleeping or pregnant. If you see your molly fish lying down on the surface of your tank, it’s a good indication that something is making them unhappy. 

There are a couple of likely culprits; either the water is not to your molly fish’s liking, or your molly fish is sick. This is a behavior that these fish often exhibit when they have a swim bladder infection, which needs to be treated as soon as you suspect it. 


It is hard not to panic when you walk by your tank, only to see a fish lying still at the bottom of the tank. Thankfully there’s a good chance your fish is just trying to get some rest. It’s still important to observe your fish, so you differentiate between normal and abnormal behavior. 

Take a mental inventory of your fish and how each of them normally spends their days and nights. This will help you gain more insight into whether or not your fish just likes to relax at the bottom of the tank or your fish is trying to tell you that something’s wrong and you need to take care of it.


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