Why is My Fish at the Bottom of the Tank? – 4 Reasons

why is my fish at the bottom of the tank

One day you noticed your fish laying on the bottom of the tank, what does it mean? Identifying unusual fish behaviors helps you quickly take measures to deal with them or simply won’t have to worry anymore.

Why is my fish at the bottom of the tank? Well, fish laying on the ground is normal behavior when it happens regularly. But if it’s new, your fish may get some distress or disease.

You need to figure the cause out. Let’s keep reading!

Reasons Why My Fish at the Bottom of the Tank


1. Fish’s Normal behavior

It might not be an alarming issue, and just normal fish behavior if yours stay at the tank bottom. Below are some common reasons for such a behavior:

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  • Bottom dwellers


If you see your fish at the bottom of the tank, not moving, it just might be that they are bottom dwellers. The typical fish that love to stay deep in your aquarium include Kuhli Loach, Corydoras Catfish, Plecostomus, Otocinclus, Twig Catfish, and some types of loaches, etc.

Such species spend lots of their active time at the bottom of the aquarium, resting and looking for food or exploring the low plants.

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  • Bottom feeding fish



Corydoras Catfish is the typical bottom feeder as well as a dweller. If you have them in the tank, it’s normal to see these peaceful fish feeding and swimming at the bottom, so do not worry.

Typical bottom feeders also include flatfish, cod, bass, some types of catfish, and loaches.

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  • Resting time


Fish chilling near the ground is completely normal for some fish species. Some fish sleep at the bottom of the tank for about 9 – 12 hours every night.

Therefore, it’s perfectly normal when you see your fish at the bottom of the tank on its side and still breathing. They’re just resting.

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  • Old fish


Most fish living in aquarium tanks have an average lifespan of around 3-5 years. Some of them might tend to take a rest and sleep at the bottom of the tank more often once they get older.

Betta fish is a perfect example in this case. They will prefer resting at the bottom of the tank once they age. So, don’t worry when you see your fish at the bottom of the tank, they might be just sleeping most of the time.

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  • New Fish


New fish tend to find hiding places at the bottom of the tank where there are low-growing aquarium plants, stones, and gravel. This is a natural behavior in most fish when first brought into a new place.

Most of the time, they will get used to the tank conditions as long as the temperature, pH level, and food are appropriate. Then, after a week or so, they will spend less time at the bottom.

2. Concerning reasons


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  • Aggressive tank mates


If you notice your fish not eating and laying at bottom more frequently than normal, they may”get bullied” by others. Repeated bully action can seriously hurt other tank mates. So you need to figure out the harassers first and move them out.

  • Some fish are well-known as aggressive habitants to other creatures in the tank, so knowing the compatibility among your fish is essential.
  • Besides, you can get a larger tank with more aquarium decoration and plants for all the fish to have space to swim around.

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  • Territorial behavior


A territorial fish might lie on the ground to mark up its domain. It’s a normal action, but if your tank is too small, some fights for territory can happen, as not all of them can survive in a confined space.

  • To avoid fish hurting each other, always choose a big fish tank instead of a small one. This makes sure your fish have enough space to claim their territory.
  • Creating visual boundaries in the tank by adding some high decorations like live plants can also have a very good effect in keeping territorial fish away from the bottom.

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  • Too low or too high water temperature


You may see your fish sitting at the bottom of the tank when the temperature inside your aquarium is too low or high; why?

  • When the water temperature falls extremely low, fish tend to stay at the bottom to conserve their energy consumption.
  • In contrast, they will also lie on the ground to get maximum oxygen when the temperature in the tank increases too high.

Warm water contains less oxygen than cold water, which will cause more problems for your fish.

  • So, checking the water temperature regularly is necessary to prevent fish from getting stressed.
  • Besides, avoid keeping fish species in different temperature conditions, like tropical fish (75-80°F) and coldwater fish (<68°F), in the same aquarium.

3. Potential Diseases


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  • Ammonia poisoning


Fish swimming at bottom of tank and gasping for air are some signs that allow you to recognize when your fish get ammonia poisoning.

When experiencing ammonia poisoning, you can see your fish breathing heavy and losing their appetites.

Adding too much new fish in an uncycled tank, bacteria buildup, and overfeeding are some of the main reasons causing this poisoning.

  • To quickly solve this problem, you need to lower the pH level and do a 25-50% water change.
  • Don’t forget to restrict feedings and stop adding new fish. Remember, your fish can die after a water change, so it is essential to do this step slowly and properly.
  • Make sure you monitor the ammonia level in your tank frequently to make sure it stays at 0.

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  • Swim bladder infection


Getting swim bladder disorder may be the reason why your fish sinks to the bottom. Fish suffering from this infection will often sink to the bottom or float at the top of the tank.

They also have a bloated stomach and tend to float upside down.

Any fish species can face this infection, but it’s commonly seen in goldfish. Normally, your fish get swim bladder infections due to overeating, low water temperature, and bacterial infections.

Depending on the cause, there are different treatments, therefore, monitor your tank conditions.

  • It’s crucial to maintain the water temperature at 78-80 degrees F.
  • Stop giving the fish food for a day or two if they suffer from constipation
  • Use a safe anti-bacterial agent to treat the infection.
  • Add more fiber to the fish’s diet

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  • White spot disease


“Ich” or “white spot” disease shows itself in the white spot on the fish’s body.

When getting Ich, fish often stay at the bottom of the tank and not moving, with small white spots, which are parasites, on the skin. They also usually scratch against rough surfaces and gasp for air.

  • To treat this illness quickly and successfully, it’s better to invite a veterinarian to examine your sick fish and follow the instructions.
  • Regularly check the water temperature to know whether all parasites in your tank are eliminated or not. It’s best to maintain a water temperature of 80°F for warm-water fish.

4. Wrong water parameters


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  • pH Levels


Fish tend to stay on the ground when the pH level in a tank drastically drops or spikes. Although it is normal when the pH in a tank fluctuates, your fish may get stressed, sluggish, and even die when the pH level is too low or too high.

Therefore it is necessary to check the pH daily and bring it to the optimal level to prevent fish stress and other diseases. The ideal pH level in your fish tank ranges from 6.8 to 7.8.

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  • Ammonia Level


Ammonia poisoning is also one of the reasons why your fish stay at one corner of the bottom more frequently than usual.

Ammonia can be very toxic, and the ideal level of ammonia is always 0. Make sure to keep the ammonia level in your fish tank less than 1ppm if you don’t want your pets to get poisoned.

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  • Nitrites Levels


When experiencing nitrate issues, your fish will lie on the tank bottom and show signs of hard breathing, rapid gill movement, and avoiding eating.

Your fish may get Nitrate poisoning or Nitrate shock depending on the level of exposure. They also can die within 24 hours when nitrate levels suddenly spike. Therefore, it’s crucial to check and remove the source of the problem before having any new fish.



How to tell if your fish is old?

Here are some signs of fish aging you can easily notice:

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  • Look emaciated
  • Start losing much weight
  • Loss of appetite
  • Struggle to breathe
  • Skin starts losing vibrant color
  • Prefer to stay still in one corner


Can a fish recover from stress?

Normally, a fish can recover from stress, this may take hours or days. But in some cases, your fish can not recover due to a shock change. Fish are so sensitive they can get stressed only after cleaning the tank, for example, so you need to monitor their behavior regularly.

To help your fish get over stress faster, you can make some changes in the tank by adding more decorations and plants.

What should I do when nitrite levels are high in a fish tank?

Here are several ways you can use to lower nitrite levels in your aquarium when it’s high.

  • Confirm nitrite level and do a 25-50% water change
  • Adding a cycled filter to release bacteria, they will eat all the nitrites
  • Stop feeding your fish temporary
  • Increase oxygen levels by adding some chlorine salt


It’s important to know why is my fish at the bottom of the tank right? Monitoring your fish closely will prevent them from disease and illness as well as take action timely.

Nothing to worry about if your fish love hanging out and chilling at the bottom, but if this behavior is new, you need to investigate the reason behind it to propose proper measures.