Why Do Cory Catfish Play Dead? (Reasons+Solutions.)

Cory catfish are easy to take care of as they are hardy fish, which makes them the best option for beginners. Also, they are the most common bottom dwellers aquarists prefer to add to their tanks.

However, sometimes they show strange behavior, like acting dead, which becomes a matter of concern as we all think they have passed away. So, Why do cory catfish play dead? Let us find out.

Cory catfish play dead when they are not in their best health and want to hide from the aggressive fish and avoid getting threatened. Other reasons are stress and poor water condition. Avoid adding aggressive fish, and ensure good and adequate water conditions and parameters to prevent such issues.

This article will discuss the reason behind cory catfish playing dead, and also, we will discuss how to know if my cory catfish is dying. So, let us get into it.

Why is my cory catfish acting dead?

Your cory catfish can act dead when kept in poor water conditions and stressful environments.

Keeping them in a small group, the presence of aggressive fish, and overcrowding can also be the reason for your cory catfish showing such strange behavior.

Cory catfish are hardy fish and can live in a wide range of water conditions, but keeping them in inadequate and dirty water conditions will make them stressed and show such behavior.

Cory catfish playing dead indicates to you that something wrong is going on and needs immediate action.

There can be various other reasons for your cory catfish acting dead, which we will discuss in this article.

Also read: Why Are My Cory Catfish Hiding?

Is it a normal behavior of cory catfish to play dead?

It is not normal for a cory catfish to play dead.

If your cory catfish is acting dead, it is a matter of concern as something is going wrong with them.

There can be numerous reasons for your cory catfish showing such behavior.

If the reason for such issues doesn’t get solved, then it is possible that your cory catfish can even pass away.

Keep a regular check on your cory catfish and make sure to provide them with ideal water conditions and parameters.

The presence of aggressive fish and living in an overcrowded or small tank can also make them show such strange behavior.

What are the reasons behind my cory catfish playing dead?

All these are the possible reason behind your cory catfish playing dead:

  1. Poor water conditions
  2. Inadequate and unstable water parameters
  3. Presence of aggressive fish
  4. Overcrowded tank
  5. Keeping in a small group
  6. Feeding irregularly
  7. Illness

Poor water conditions

Poor water conditions can be the primary reason your cory catfish shows such strange behavior.

Bad water quality will make them weak and stressed out, becoming prone to various diseases and parasites. 

Cory catfish living in poor water conditions will act dead because of being under stress. 

How to solve this issue:

Perform a weekly water change of at least 35% to keep the water clean. 

Add a good filtration system with biofilter media and carbon to keep the water safe from ammonia and nitrite and maintain crystal-clean water.

Inadequate and unstable water parameters

Inadequate water parameters will make your cory catfish show such behavior. 

They will lose their appetite living in inadequate water parameters and become weak. 

You will notice your cory catfish staying at one spot or acting dead when living in inadequate water parameters.

Also read: Ideal pH Level For Cory Catfish?

How to solve this issue:

Maintain water temperature at 70-82 °F, pH level between 7 and 8, TDS between 400-600ppm, and water hardness should be between 5 and 19dGH.

Consider adding a heater to your cory catfish tank to ensure stable water temperature.

Presence of aggressive fish

Cory catfish are peaceful fish and prefer to live with other non-aggressive fish in a community tank.

Aggressive fish will constantly chase and bully your cory catfish.

Not to get threatened by the aggressive fish, they will play dead. 

All these will make them become stressed and prone to various diseases and parasites.

Consider adding peaceful fish to your cory catfish tanks like neon tetras, guppies, mollies, zebra danios, and platies.

Also read: Can Cory Catfish Live With Neon Tetras?

Overcrowded tank

An overcrowded tank will stress out your cory catfish, and they will play dead to release the stress. 

A crowded tank doesn’t let your fish live and swim comfortably.

Also, an overcrowded tank will have a high risk of ammonia spike and oxygen deficiency.

How to solve this issue:

To ensure that you are not overcrowding your fish tank, follow the one-inch one-gallon rule, which means one inch of fish per gallon of water.

Also read: How Many Cory Catfish In A 10 Gallon Tank?

Keeping in a small group

Cory catfish are schooling fish and prefer to live in a large group of their species.

Keeping only one or two cory catfish will make them come under stress, and they can show such strange behavior.

Keep at least 5-6 cory catfish together to form a good school for them.

Also read: Do Cory Catfish Need A School?

Feeding irregularly

Feeding your cory catfish irregularly will make them weak and prone to diseases and illness.

They will come under constant stress and will show strange behavior like acting dead.

Feed your cory catfish with various types of high-quality nutritional food to keep them healthy and safe from diseases and parasites.

Healthy fish will not easily catch bacteria and parasites.

Also read: Can Cory Catfish Eat Betta Food?


Cory catfish suffering from an illness will become weak and act dead to release their stress.

Usually, corydoras are hardy fish and will not easily be affected by any illness. 

However, conditions like poor water quality, inadequate water parameters, and a stressful environment can make them prone to various diseases and parasites.

Keep a regular check on your cory catfish’s physical appearance, as faded colors, patches on the body, and rotting fins are the symptoms of sick fish.

Treat them with proper medication, which the vet recommends if they are affected by parasites or diseases. 

Also read: How To Treat Swim Bladder Disease In Cory Catfish?

How to know if my cory catfish is dying?

You will notice physical and behavioral changes in your cory catfish when they get weak and is about to pass away.

Your cory catfish will get weak and be less interested in moving from one place to another.

They will not dig at the bottom the way they usually do and stop searching for food when about to die.

They will not be interested in eating and will avoid eating most of the time.

You will notice physical changes like frayed fins, faded colors, bloating, and patches in the body.

However, if you notice some of these symptoms at early stages, you can treat them with medications and other ways.

Usually, poor water conditions, inadequate water parameters, and a stressful environment makes your fish weak and providing them with their ideal water conditions and parameters resolve most of the issues.

Do cory catfish sleep?

Cory catfish are bottom dwellers and spend most of their time scavenging on the bottom, searching for food.

They will take some rest for 10-15 minutes whenever needed during the day and night.

Cory catfish will fully sleep at night or in the daytime but will take rest for 10-15 minutes whenever needed.

They are active swimmers, and you will find them digging in the bottom of the tank most of the time.

They will sometimes come to the tank’s surface to gasp air from their mouth as it is their natural behavior.

Also read: Are Cory Catfish Nocturnal?

How to take care of a cory catfish?

Cory catfish are hardy fish and can live in a wide range of water parameters and conditions.

They are easy to take care of, which makes them the best option for beginners.

Provide your corydoras with ideal living conditions and parameters, and they will thrive.

They are schooling fish, and keeping them in a large group of their species will do great for them.

Also, they will love to interact and swim with other peaceful fish, so keeping them in a community tank will make them thrive.

Keeping the water clean by performing a regular water changes will prevent various issues.

Also, consider maintaining stable and adequate water temperature to prevent stress.

Feed them two times a day regularly with high-quality nutritional food that contains both plant and meat-based dietary value to ensure their faster growth and development.


There can be numerous reasons behind your cory catfish’s death, which are the primary reasons for poor water conditions and stress.

The presence of aggressive fish, feeding irregularly, illness, inadequate water parameters, and unstable water temperature will make your cory catfish weak, and they will come under constant stress, becoming prone to various diseases and parasites.

Weak and stressed cory catfish will show such strange behavior of acting dead.

They do this to keep themselves safe from other tankmates and to avoid getting threatened by aggressive fish.

Ensure good water conditions and adequate and stable water parameters, avoid overcrowding, and feed them regularly to prevent such issues.

Reference: Wikipedia, Britannica


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