7 Reasons Why Your Fish Is Lying on Its Side (5 Ways to Prevent It)

7 Reasons Why Your Fish Is Lying on Its Side (5 Ways to Prevent It)

Fish lying on its side

Most aquarium fish keep moving around in the fish tank. However, it’s not uncommon to find a fish struggling to stay upright.

So, why do some fish lie down on their side?

Reasons Your Fish Is Lying on Its Side

There are several possible reasons why your fish might lie down on its side at the bottom of the aquarium.

However, we want to highlight some common causes that can make your fish struggle to maintain buoyancy or stay upright.

Given below are the main reasons why your fish might be lying on its side.

Disease or Sickness

Your fish might be lying on its side mainly because it’s suffering from a disease or sickness.

Fish with weak immune systems are more susceptible to illnesses.

Diseases like bloat, dropsy, ich, and velvet make your fish lie down on its side.

These diseases are usually caused due to the stress caused by poor tank conditions.

Proper hygiene and adequate water conditions are prerequisites to maintaining fish health.


Bacterial or fungal infection is another reason why your fish is lying on its side.

Infections are also transmissible and easily contracted by other tank inhabitants.

You can add salt to the tank water to treat infections. However, overdosing on salt is detrimental to fish health.

So it’s essential to keep the water salinity under control with regular water changes.

Poor Water Quality

Inadequate or poor water quality is another reason that stresses your fish and impact their health.

Irregular tank cleaning accumulates decaying organisms and waste, which causes infections to fish.

Also, a clogged filter can’t remove any debris or waste. This spikes the toxin levels inside the tank resulting in poor fish health.

Inappropriate Water Temperature

If the temperature of the tank water is too high or low, it adversely affects the metabolism of your fish.

This results in loss of appetite and sedentary behavior. The fish can also suffer heat stroke if the water temperature is too hot.

These stressful conditions impact your fish’s immune system, making it struggle to stay upright.

Heavy Water Current

Water current is important in any fish tank as it helps in oxygen circulation.

However, the water current inside the tank should replicate the natural habitat of the tank inhabitants.

If the water current is too strong, it results in stressful situations as the fish will have to use a lot of energy to maintain balance.

This results in fatigue and poor health.


A sudden injury causes your fish to lie down on its side.

An injured fin or tail makes the fish lose equilibrium, and it struggles to swim.

A sudden fall or aggressive encounter with other fish can result in severe injuries, causing the fish to lie down on its side.

Swim Bladder Disorder

Fish with swim bladder disorder

A swim bladder is an organ that helps the fish maintain buoyancy.

So if a fish is suffering from swim bladder disorder, it will lose its equilibrium.

This will result in the fish sinking to the bottom of the tank, floating at the water’s surface, floating on its side, or even floating upside down.

If you see any of these symptoms in your fish, it’s essential to get it checked by a veterinarian immediately.

There is no cure for this disorder, but there are ways you can help ease the discomfort that it causes your fish.

Ways to Prevent a Fish from Lying on Its Side

Fish having difficulty in swimming or maintaining buoyancy should be taken to a vet.

However, avoiding or preventing your fish from developing such a condition is ideal.

Given below are some ways to prevent a fish from lying on its side.

Feed a Well-Balanced Diet

A well-balanced diet helps improve the immune system and is critical for the overall development of the fish.

Depending on the dietary requirements of your fish, feed them a healthy, balanced, and appropriate diet.

It’s also critical that you understand the appetite of your fish because you don’t want to overfeed or underfeed them.

Make sure your fish get enough protein and fiber to keep them healthy.

A well-balanced diet will ensure that they don’t become susceptible to infections.

Maintain Pristine Water Quality

Another way to prevent diseases and infections is by maintaining pristine water quality inside the aquarium.

It’s crucial to monitor the water parameters continuously.

This will ensure that the ph, hardness, ammonia, nitrite, and nitrate levels are always within the desired range.

Good water quality will improve the immune system of your fish and help them develop resistance against diseases and infections.

Provide a Conducive Tank Environment

A conducive tank environment is another critical factor that can help prevent fish diseases and infections.

Depending on the fish species, use a heater or chiller to keep the water temperature constant.

Also, perform regular tank maintenance to remove debris and unwanted particles from the tank.

Clean water, appropriate water temperature, adequate swimming space, and proper hiding spots will ensure that the fish enjoy their environment and feel safe and comfortable.

Avoid Overcrowding

The aquarium must have adequate space for all the tank inhabitants.

Keeping too many fish in a small tank will stress them as they will not have enough space to move around.

Overcrowding will also result in a spike in the toxin levels of the tank water due to the high amount of fish waste getting produced.

This will affect the immune system of the fish and make them susceptible to various diseases.

Monitor Regularly

Monitoring the water parameters is essential for keeping your fish healthy.

However, it’s also essential to monitor the health of your fish.

Provide necessary medication or seek medical assistance if you find your fish in discomfort.

Regularly check for early signs of stress or infections to ensure that they don’t result in significant issues for your fish.

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