Why are my fish at the bottom of the tankFish at the bottom of the tank can be due to several reasons. But first, rule out the possibility that your fish is a bottom dweller and prefers the bottom part of the tank. Another reason your fish is hanging at its tank’s bottom is it could be stressed.

Nevertheless, read this article to discover various circumstances that would make a fish stay at the bottom of the tank.

Why Are My Fish at the Bottom of the Tank

There are several reasons a fish spends a lot of time hanging at the bottom of the tank. Here are some of them:

1. Stress

Your fish sitting at bottom of tank can be due to stress. To detect a stressed fish, you would notice fading in its color. Also, the fish would naturally sink to the bottom of their tank. Stress is due to two factors;

  • External fish stress
  • Internal fish stress.

External fish stress refers to external factors that cause your fish discomfort, making it spend more time at the bottom of the tank. However, you should consider the internal fish stress if your fish is not exposed to any external stress. Below are some reasons why your fish is at the bottom of its tank and solutions.

2. Habitat Change

Fish staying at bottom of tank shouldn’t bother you yet. This is because your fish may be stressed due to a recent tank change. Moving to a new apartment is typically stressful for humans, likewise fish. Even if you move their tank from one room to another in the same house, this will happen.

They need time to adapt to their new environment. However, you can avoid stress by purchasing some counter drops specifically for fish stress at a pet store.

3. Noise Pollution

Noise pollution can also cause fish stress because water amplifies sound. So, you must keep television sets and other sound devices away from their tank. Also, friends and family should avoid tapping the glass wall of the tank. The sound could scare the fish and cause it to try to hide at the bottom of the tank.

Furthermore, some tank filters are very noisy, so check if the one installed in their tank isn’t too loud. The loud noise generated can cause fish to swim on the bottom of the tank.

4. Pets

Your fish lying on the bottom of a tank can be because of your other pets. Some of them spend a lot of time staring at the fish tanks causing the fish to become scared and depleted. Also, the fish constantly feels like prey under the watchful predatory eyes of the dog or cat.

Furthermore, some pet cats are more daring, and they may try to catch the fish by dipping their paw into the tank. So, keep the tank closed or put the tank in a room away from the pet. It would help the fish relax more and enjoy swimming around.

5. Lighting

Balance is essential, especially when tank lighting is involved. Some fish are active at night, while the diurnal fish move around during the day. Hence, creating the illusion of night and day in a fish tank is necessary as it imitates their natural habitat. A fish without this balance can become confused and stressed. You can solve this issue by installing adequate lighting or placing the tank close to direct sunlight.

6. Rapid Temperature Fluctuations

A fish is vulnerable to rapid temperature changes and could go into shock. So, be sure your heater and thermometer are functioning correctly. Also, ensure your heater is powerful enough for your tank size because each fish species have a specific temperature requirement.

Furthermore, extremely high temperatures in a tank can affect the fish’s oxygen level. Therefore, inadequate oxygen can cause strange behavior like fish hanging out at bottom of the tank. Additionally, low temperatures make a fish behave sluggishly as it is not warm enough to swim around.

7. Incompatible Tank Mate

If you are a novice hobbyist and have not done adequate research, you may have placed incompatible fish in your tank. Hence, they will not get along and would be stressed.

Furthermore, if you keep a community tank and already own a variety of fish species, you should add only fish compatible with the existing breed. Nonetheless, if you already have two fish that pass aggression by chasing each other or fighting, you need to set up a different tank.

8. Fish Disease

Your fish laying on bottom is not abnormal if it is ill. Closely monitor it to observe other signs like sluggishness, irregular swimming pattern, unusual spots on the fish body, and bloated appearance. Other symptoms include breathing problems, a patchy or slimy body, and frayed fins.

If your fish has any of these symptoms, you need to isolate and treat it, especially if it is a community tank. Also, perform a complete water change to reduce the chances of an outbreak.

9. Overcrowded Fish Tank

An overcrowded tank can make your fish experience internal stress because the water quality drops rapidly. If the water parameters are unstable, the fish would naturally be stressed.

Please note that these fish are also used to unlimited space in the wild. Hence, four grams of fish to one liter of tank space is ideal. But, this excludes decoration and plant space. You can improve your fish’s living conditions by adding some plants to boost oxygen levels.

10. Bottom-dwelling fish

Fish swimming at bottom of tank is not uncommon for a natural-born bottom feeder and dweller. Most bottom-dwelling fish are comfortable there and tend to blend into the environment naturally. They also eat algae and debris found at the tank bottom.

So if your fish is a freshwater fish like corydoras catfish, otocinclus, plecostomus or kuhli loach, it would stay at the tank bottom. Another way to detect if your fish is a bottom feeder is to check where its mouth is located. If it is at the bottom of the fish head, it is likely a bottom-feeding fish species.

11. Sleepy Fish

Your fish is probably sleepy; that’s why it is hanging at the bottom of the tank. Yes, fish need about nine to tewelve hours of sleep per day to function correctly. But, they do not have eyelids, so you may not be able to tell when they are asleep. To tell when a fish is napping, you would notice small fin and tail movement.

Also, the fish’s breathing pattern would be less rapid with its mouth and gills. They would rest for long hours under rocks, plants, and tank bottom. But, if your fish is sleep-deprived, it would be stressed. Wrong tank mates and inappropriate noise and lighting are some factors that cause fish sleep deprivation.

12. Old Fish

Your fish may be lying at the bottom of your tank because it is dying. It may be old and weak, so it stays at the tank bottom and barely moves. Hence, you need to rule this out if you have had your fish for a long time.

Would Wrong Water Parameters Cause My Fish To Hang at the Bottom of the Tank

Yes, wrong water parameters can stress out a fish causing them to become slow. They would prefer to sit at the bottom of the tank as their habitat will restrict them from doing much. If you notice these, you should check the different water parameter levels to ensure they are within the required specifications.

Here are some levels to check.

1. pH Levels

It is not uncommon for the pH in a tank to fluctuate. However, it is necessary you maintain the pH levels, so your fish is healthy. Also, drastic drops or spikes in pH levels can be fatal to the fish in your tank. You can prevent fish stress and death by testing the pH levels often. Furthermore, clean your fish tank thoroughly and ensure the water quality is optimal.

2. Ammonia Level

You should check the Ammonia range in your tank to keep your fish healthy. The ammonia levels should be less than one part per million for a freshwater aquarium. If it is higher, your fish can develop ammonia poisoning. Ammonia poisoning is commonly overlooked in many home tanks but highly toxic and fatal.

They are due to overcrowded tanks and inefficient tank filters. Also, ammonia poisoning happens when medication from treating a sick fish kills both the parasites present in the tank and the beneficial bacteria that keep ammonia levels low. Nonetheless, high ammonia levels can cause the fish to hang out at the tank’s bottom frequently.

– Signs To Help Detect Ammonia Poisoning

You can test the water using an ammonia test strip. Alternatively, observe the fish to see if they are exhibiting any of these signs.

  • Lazy behavior like sluggishness
  • Reddish or purple gills
  • Red stripes on fish body
  • Less appetite
  • Fish hanging out at bottom of tank

If you discover your fish tank has high ammonia levels, here’s what to do to manage the situation fast.

  • Reduce feeding your fish or stop completely
  • Reduce the tank pH levels to below 7.0
  • Siphon half of your tank water out, then replace it with clean water
  • Use chemical additives to treat your water

3. Nitrites Levels

If the ammonia levels are high in the tank, nitrites would also increase. Hence, high levels of nitrate would affect the fish’s behavior. When experiencing nitrite poisoning, the fish would stay near the tank filter outlets, gasp, and breathe fast, in addition to, the fish gills appearing tannish. Similarly, it would hang out at the bottom of the tank because it is stressed.

– Negative Impacts of Nitrite Poisoning on Fish

  • Inability to metabolize oxygen in their blood
  • Decrease immunity with little or no defense against illness
  • Increased bacterial infections


1. How To Tell If Your Fish Is Old?

  • They begin to emaciate
  • Their eyes start to bulge
  • They tend to eat less
  • Their skin begins to lose its once vibrant color
  • They would float using their sides
  • They would hang out more at one corner of the tank
  • They may have trouble breathing

Furthermore, research to find out the life span of your fish, some fish may live for just two years, while others up to ten years. However, the life span can reduce if the care it has received had not been up to its standard requirement.

2. Can a Fish Recover From Stress?

Yes, a fish can recover from stress. You can nurse your fish back to health with proper care and patience. But, it may take hours or even days, depending on the impact they were exposed to. However, in some cases, the fish may not recover and die.

3. What Should I Do When Nitrite Levels Are High in a Fish Tank?

Fish at the bottom of the tankFirst, confirm using a test strip and observe your fish behavior. Then, check that the nitrite level is 0-.2mg/l. and gradually do a 50 percent water change.

It can be about five percent of the tank volume each time, so the fish doesn’t go into shock. Also, temporarily stop giving food to the fish. Then, add some chlorine salt into the aquarium and install an air stone to increase oxygen levels.


It is important to note that some fish like to hang out at the bottom of the tank. So, here are some pieces of information to remember:

  • An ill fish would spend more time at the bottom of the tank
  • Old age can cause a fish to become sluggish and hang at bottom of the tank
  • Incorrect water parameters can cause fish to stay at the tank’s bottom
  • Conflicts from inappropriate tank mates can stress your fish
  • A fish requires up to nine hours of sleep

Nonetheless, ensure the fish is comfortable in the tank. Which of these reasons why a fish is at the bottom of the tank applies to you?

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