Why Do Fish Lay at the Bottom of the Tank? (Reasons + Solutions)

Interested in reasons fish lay at the bottom of the tank? This guide is for you!

Have you noticed your fish lying at the bottom of the tank, and you have no rational reason for it? This can be disturbing, especially if it is a recently acquired behavior.

There are perfectly normal reasons your fish lies at the bottom of the tank. For example, it could be that you’re dealing with a bottom dweller, or that your fish is just resting. And then there are concerning explanations for this behavior, such as this fish is sick or is hiding from something.

The normal reasons are actually non-concerning; they are expected of your fish and its kind.

The concerning reasons indicate that something is wrong. Here, your intervention is required to set things right.

Either way, we’ll help you identify and interpret this behavior and guide you on what best to do in each situation.

fish laying on bottom of tank

Why Does My Fish Lie at the Bottom of the Tank? – Normal Reasons

#1 – Your Fish is a Newcomer

Is your fish new to your home, or have you just changed his tank? When fish find themselves in a new environment, they prefer to lie at the bottom of the tank, where they feel it is safest and most secure.

This often happens if there are other fish in the tank. However, you may also see it if your fish is the only one in the tank.

In this case, give your fish time to acclimate to the new surroundings. He will resume normal behavior in a few weeks.

#2 – Your Fish is Resting

Like humans, fish need to rest and escape the bustle of their routine life. But, again, just like us, these aquatic animals choose to do so in the safest and most comfortable places.

If your fish is active during other times, laying at the bottom of the tank could indicate he’s taking a break.

Indeed, it is important to encourage your fish to take such rests by keeping the lights on a diurnal schedule.

#3 – Your Fish is a Bottom Feeder

Bottom feeders are fish that prefer to forage at the bottom of the tank for food. You’ll notice they retreat to the bottom just before feeding time.

They enjoy gulping the food as it sinks to the bottom, and will remain there for some time to look for leftovers among the gravel.

Others prefer to take some time off and rest at the bottom of the tank after feeding.

#4 – Your Fish is a Bottom Dweller

Some fish are designed to spend their active hours at the bottom of the tank. This is where they live their lives, and are inclined to stay close to the low-growing plants at the bottom.

To make the lives of these species more exciting, plant a mini-aquatic jungle on the lower levels of the aquarium.

Examples of bottom dwellers include plecos, cory catfish, and loaches.

#5 – Your Fish is Elderly

Age is catching up with your fish!

This is good news; you’re doing a stellar job nurturing your pet fish to the very zenith of its life. As a pet parent, you are doing well.

Generally, most species of fish live for about 3 to 5 years. As they near the upper limit of their lives, they take more extended rest periods at the bottom of the tank.

This is perfectly normal for fish; nothing to be worried about.

Why Does My Fish Lie at the Bottom of the Tank? – Concerning Reasons

#6 – Improper Lighting

Lighting is an essential component of your fish’s life. It helps this animal maintain the right circadian rhythm.

Nocturnal fish are active at night, while diurnal fish do their activities during the day. And then we have the crepuscular fish, which are active at dusk and dawn.

In the wild, all these fish are guided by the sun’s rising and setting to set their circadian rhythm. However, in captivity, they depend on the lighting you install in the tank to guide them.

Red Flags

Suppose you are dealing with a diurnal fish, for example, and you find him lying at the bottom of the tank instead of being active.

In this case, it could be that the fish is unaware it is daytime. However, the poor lighting creates the illusion it is nighttime, and your fish is sleeping, waiting for daylight to arrive.

Improper lighting can create confusion and imbalance, leading to a raft of other health issues.

What to do

You can solve this by installing a proper lighting system, equipped with a timer to regulate the daytime and nighttime hours.

Ordinarily, a fish requires 12 hours of daytime and 12 of night – just like in their natural habitat. But, of course, you may have to occasionally adjust to move with the year’s seasons.

#7 – Hiding from Something

If your fish is a top or mid-level swimmer, it should raise the alarm when they spend most of their time at the bottom.

Does the fish have aggressive tank mates? You could be dealing with a case of bullying.

Red Flags

The fish gets nipped at by the tank mates whenever he tries to resume his rightful position in the tank.

Clearly, there’s an issue of incompatibility. However, it could also be that the tank is not large enough or overstocked.

What to do

Add more distractions to the tank to keep all the fish occupied. These include live aquarium plants and decorations.

You could also remove the aggressor from the tank and relocate them. This will help you avoid having to handle cases of severe trauma.

If the tank is overcrowded, consider investing in a bigger aquarium. On the other hand, it would be a good idea to offload some of the stock if it is overstocked.

Also, evenly distribute the fish in your tank among surface dwellers, mid-level swimmers, and bottom dwellers.

Don’t have too many of any of these types of fish.

#8 – Territorial Behavior

A fish may lie at the bottom of the tank to assert his dominance in this part of the territory.

Red Flags

There will be frequent fights for dominance among the fish. This could also indicate that you have too many bottom dwellers, with many claiming stake in the prime areas at the bottom.

What to do

Invest in a large enough tank if you have many fish known to claim the bottom of the tank as their territory. Allow each fish enough space to feel safe and comfortable.

#9 – Poor Water Quality

All fish react negatively to a drop in water quality. While some are more tolerant, others react even at the slightest fluctuation in pH.

Poor water quality is one of the significant causes of stress and low immunity in aquatic animals.

Red Flags

The fish hugs the bottom of the tank. Sometimes, these animals become lethargic to indicate they have been severely affected.

The less tolerant fish are hit the hardest. They may come down with fungal and bacterial infections as a sign that their immunity has been severely compromised.

What to do

Closely monitor the water parameters at all times. In fact, you should have dedicated devices installed for this task.

Using the proper aquarium test kits, keep a close eye on pH, salinity, and water hardness. Regularly test for ammonia, nitrate, and nitrite concentrations.

# 10 – Flawed Water Temperature

If the water temperature is too high – and for some fish, too low – problems arise.

Your fish will be forced to seek refuge at the bottom of the tank, hoping to find more favorable temperatures.

Low water temperatures force the fish to lie at the bottom of the tank to conserve energy.

On the other hand, high water temperatures make the fish swim to the bottom, where oxygen concentrations are higher.

Red Flags

A fish that lies at the bottom of the tank and has labored breathing likely suffers from temperature issues.

And so is one that swims erratically for brief periods before rushing back to the bottom of the tank. But, again, this is a sign that temperatures have risen too high.

Other signs of untenable water temperatures include bloating, loss of appetite, or overeating.

What to do

Control the tank heating needs the proper way, by using a heater with a digital controller. This is a device that ensures the heater is emitting the correct wattage as per your settings.

Of course, before setting the heater, you need to know the heating needs of the fish in your tank.

Different fishes thrive in different temperature ranges. This is why tropical fish cannot live in the same tank as coldwater species.

Their temperature needs are on the different ends of the spectrum.

#11 – Your Fish is Sick

Disease can force your fish to seek refuge and solace at the bottom of the tank.

A number of factors can contribute to your fish falling ill. These include poor water quality, improper feeding, and stress.

If there’s an outbreak of disease in the aquarium, quickly quarantine the diseased fish in a separate tank, where they can be attended to by a vet.

Here’s a look at some of the diseases that may force your fish to retreat to the bottom of the tank:

Physical Trauma

If the fish lying at the bottom of the tank is injured, this is a recipe for disaster. Open wounds in fish (and other animals) lead to infection.

You need to act with speed and quarantine this fish for specialized care.

Causes of physical trauma

  • Territorial fights
  • Bullying
  • Fin nippers
  • Accidental injuries from sharp objects and rough edges
  • Fights for mating rights
  • Overcrowding

Treatment for physical trauma

  • Have the fish quarantined and the injury attended to.
  • Fish known to fight for territory or dominance should not be in the same tank.
  • Don’t put aggressive fish in the same tank.
  • Separate bullies.
  • Smoothen the rough edges and replace sharp decorations.
  • Acquire a bigger tank to accommodate all your fish.

Ammonia Poisoning

Ammonia is a byproduct of the waste in the tank. If the tank is not cleaned regularly, the bio-load becomes too high, and most is degraded into ammonia.

Ammonia poisoning is a serious condition characterized by labored breathing, a loss of appetite, and lethargy.

Fish with ammonia poisoning tend to move to areas with higher oxygen concentrations, such as at the bottom of the tank or near the filter.

Causes of ammonia poisoning

  • High bio-waste
  • Overfeeding
  • Overcrowding
  • Depletion of good bacteria

Treatment for ammonia poisoning

  • Regularly check the ammonia levels in the tank using the appropriate aquarium test kits.
  • If the ammonia level reading is above zero, it is a red flag. Take immediate remedial measures.
  • Change 25% of the tank water weekly.
  • Clean the tank regularly.
  • Use filtered, bottled, or de-chlorinated water only.
  • Avoid overfeeding your fish.
  • Acquire a larger tank to avoid overcrowding.

Ich Disease

Ich disease (Ichthyophthirius multifiliis) is a serious condition that forces your fish to move to the bottom of the tank.

The fish develops white itchy spots that compel it to rub itself against the tank floor and other surfaces.

Your fish displays obvious signs of distress, such as erratic swimming, appetite loss, and irritability.

Causes of Ich disease

  • Compromised immunity
  • Water temperature fluctuations
  • Improper feeding
  • Poor relocation from one place to another
  • Parasitic attacks
  • Stress from tanks mates
  • Any other source of stress

Treatment for Ich disease

  • Put your fish on a proper diet to ensure strong immunity.
  • Raise the water temperature to kill offending parasites.
  • Maintain water temperature at 260 C to 270 C (780 F to 800 F) – This should not be done to coldwater fish.
  • Regularly and safely give your fish a potassium permanganate bath.
  • Quarantine the affected fish and medicate them with methylene blue, formalin, copper sulfate, or malachite green for 2 weeks.

Swim Bladder Disease

This disease is characterized by the fish’s noticeable loss of swimming control. This animal swims on its side and sometimes upside down.

If you see your fish at the bottom of the tank behaving this way, it is affected by this disease. Your pet’s swim bladder has been infected and cannot help him maintain the proper balance in the water.

Fish that suffer this condition float at the tank’s surface or bottom.

Causes of swim bladder disease

  • Poor water chemistry
  • Overfeeding
  • Bloating
  • Constipation
  • Bacterial infection
  • Egg binding in females
  • Kidney malfunctions

Treatment for swim bladder disease

  • Regularly check the water quality and promptly address any issues arising.
  • Avoid overfeeding your pet.
  • Give this fish a 2-day fasting period to unclog the digestive system.
  • Feed your fish more fiber to relieve constipation.
  • Consult the vet to help resolve the issue of egg binding in females.
  • Use aquarium salts to relieve bacterial infections.
  • If the problem is due to deep-level infection, consult your vet for the proper diagnosis and treatment.

What to Do If Your Fish is Lying at the Bottom of the Tank

As earlier noted, your fish could be lying at the bottom of the tank for various reasons.

While some of these reasons are innocent and should not bother you, others require you to take action to help your fish overcome the challenges he’s going through.

The good news is that, with a positive attitude, you can always resolve any potential hurdles your pet fish faces.

Here are a few tips to make your fish come from the bottom of the tank and resume his everyday life.

Monitor Water Temperature

There is an uncanny correlation between water temperature and oxygen supply. When the water temperature is too high, the fish’s metabolism increases, and he needs more oxygen.

To get this extra oxygen supply, your fish will go to the bottom of the tank, exhausted. This is because there’s usually a more abundant supply of oxygen at the bottom than in the middle of the tank.

Unfortunately, this oxygen may not sustain this animal for long unless you slow down his metabolism by lowering the water temperature.

On the other end of the spectrum, the fish will experience challenges if the water is too cold. In this case, the fish lies at the bottom of the tank to conserve energy.

The solution to both problems is to monitor and control the water temperature. Use a heater with a thermostat attached to a thermometer to perform this task automatically.

Of course, you’ll have to check these devices occasionally to ensure they stay well-calibrated.

Test the Water Regularly

Fish laying at the bottom of the tank is a sign of stress, most likely caused by poor water chemistry. This happens when ammonia, nitrates, and nitrites build up.

These chemicals can be hazardous to your pet’s health. As such, you need to constantly test the water for them.

Remove Bullies to a Separate Tank

A core reason your pet fish remains glued to the bottom of the tank is the presence of unruly tank mates.

Your fish stays glued to the bottom because of harassment. This is your cue to remove the bullies to a separate tank.

This will alleviate the victim’s stress levels, and encourage him to move from the bottom and resume his everyday life.

Check for Fish Compatibility

Not all fish can cordially stay in the same space. Actually, some fish are meant to stay alone. For example, putting two male bettas in the same tank would be disastrous.

Seeing your fish lying at the bottom of the tank most of the time indicates incompatibility with the tank mate.

Find out about the compatibility of fish species before putting them in the same space. This should be done at the point of purchase.

Quarantine Sick Fish

A fish lying at the bottom of the tank suggests the fish is unwell.

Investigate this, and if valid, quarantine the fish in a tank hospital, where he will receive specialized medical care, away from the healthy fish.

Add Adequate Resting and Hiding Spots

If, after investigating, you determine that your fish is just resting or sleeping at the bottom of the tank, you need to add more resting spots.

A closer look at the aquarium will reveal it doesn’t have enough plants, decorations, and toys. Provide your fish with a variety of hiding places and toys to keep them busy and happy.

Additionally, this will alleviate your fish’s stress levels, making them generally happier.

Get a Bigger or an Extra Tank

Putting a group of fish in one tank has its advantages. They create a visual allure like you can see in no other place.

However, if you put too many of them together, the problems associated with overcrowding set in.

Some fish will be forced to spend time at the bottom of the tank due to a lack of space elsewhere.

You can easily solve this problem by upgrading your fish tank to a bigger one. Alternatively, purchase an additional tank to decongest the first one.

Put the Tank in a Better Place

Is your fish tank in direct line to the sun? Is the room too warm or too cold? Does it have too much light or noise?

These are some of the areas you should avoid placing your fish tank. Environmental disturbances easily stress fish, and they may resort to hugging the bottom of the tank as a refuge.

To resolve this, place the tank in a place convenient for the fish. Remember, everything you do about this tank should be geared towards providing safety and security for the fish.

Change the Diet

For your fish to be well-balanced and adjusted, it needs to eat well. In addition, following the proper feeding schedule will improve your fish’s immunity.

A proper diet enables your fish to lead a healthy, happy, stress-free life. You’ll minimize or eradicate instances of your fish dealing with health-related infirmities.

If your fish has been lying at the bottom of the tank for some time, you need to change his diet. But perhaps, this is all your aquatic friend needs to be up and running all over the tank again.

Be Patient with New Comers

New fish are stressed by changes in the environment. Therefore, you need to be patient with your new fish; allow him to acclimate to the new surroundings.

As such, don’t worry when he goes straight for the bottom of the tank and remains there for some time.

This animal just wants to be sure he’s in no real threat. Before long, he’ll gain the confidence to come up and frolic about the tank.


Are you concerned that your fish is lying at the bottom of the tank? Before you go any further, consider that some fish like hanging out there.

However, if this is a recent development, you should find out the cause of this behavior.

You’ll discover that it is caused by innocent reasons, such as old age, or something else that requires your intervention.

If your fish is comfortable, safe, healthy, and well taken care of, you don’t really have to worry about it.

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