Why Is My Cory Catfish Laying On Its Side?

A cory catfish that is laying on its side could just be resting. However, if the behavior persists, do not rule out the possibility of illness. Swim bladder problems could be the culprit. Stress or overcrowding could also be another contributing factor.

Any aquarists will agree that although cory catfish are peaceful and calm, they are also quite energetic and hardworking. They may be known to stand still for short intervals, but a happy cory catfish will never just lay on its side and accept defeat.

The Reasons Why A Cory Catfish Will Be Laying On Its Side

On average, the lifespan of a cory catfish is about five years. If the tank conditions are favorable, the result is a happy cory catfish. In this instance, it is not unusual for that life expectancy to extend well beyond five years.

It is no wonder that a cory catfish found laying on its side for an extended period can cause some alarm. There are a few possible reasons for this scenario.

Front View of Threestripe Cory Catfish

Cory Catfish Is Resting

A cory catfish is known to be diurnal and crepuscular rather than nocturnal. Hence their activities peak during the day and even in the twilight.

Although their senses are heightened during this period, due to their peaceful and calm demeanor, it is not uncommon to see them lying on their side at any given time.

Most other fish species, when active, will be found swimming around profusely; with cory catfish, this is not always the case.

Since they are bottomless scavengers, they often rummage for food, yet they may still appear motionless during this time.

There is no specific way they sleep and choosing to lay on their side may be one of their preferred sleep styles.

Cory Catfish Is Dead

Although the cory catfish has a lifespan of approximately five years, often due to unforeseen circumstances like stress, old age, or sickness can have adverse effects on the fish’s well-being.

These factors can sometimes result in death. A lifeless cory catfish on its side could be the tell-tale sign of death.

Cory Catfish Is Stressed

A change in a cory catfish’s behavior is often a sign of stress, especially one found laying on its side. Overcrowding or space restriction is two common factors that cause this fish species to become stressed.

Since a cory catfish is a shoaling fish, they prefer to swim around in groups. A minimum of six cory catfish should be kept together in a tank of 10 gallons or more.

A tank of a lesser capacity can restrict the cory catfish’s movement when swimming and rummaging for food. Like humans, cory catfish also require companionship; a lonely fish may become withdrawn and want to lay on its side.

There is also competition for food when there is overcrowding, not to mention the fish detritus, which can cause the tank to become unhygienic.

Cory Catfish Is Sick

A healthy cory catfish is often a happy one. A tell-tale sign of a happy fish is usually swimming around or active. Even if they are still, it may be for short intervals.

One that is sick may display lethargy by laying on its side.

Cory Catfish Has Swimbladder Issues

Inappropriate water temperatures can cause swim bladder issues. If the water is too cold, it will slow their digestion, resulting in constipation and swim bladder problems.

Watching your cory catfish lay on its side in pain may signify swim bladder issues.

Overfeeding can also exacerbate swim bladder, resulting in bloating and an enlarged gastrointestinal tract.

Treatment For Cory Catfish Laying On Its Side

Once you have determined why your cory catfish is laying on its side, you can start with the necessary treatment where possible. If you are unsure of the cause, consult your local vet.

Dead Cory CatfishNeeds instant removal from the tank, which should be cleaned immediately.
Sick Cory CatfishThe fish should be removed from the tank and kept in isolation to prevent other fish from being infected.

Contact your local vet to check if any medication can be administered.

Stressed Cory CatfishIf the tank is too small, consider a larger tank.

Ensure that the tank is always kept clean and eliminate overcrowding.

Ensure that the cory catfish is kept with a minimum of six of the same species.

Swim Bladder IssuesSwim bladder treatment can be given to a cory catfish to treat swim bladder issues.

Ensure you do not overfeed the cory catfish; feeding should be twice a day. Their consumption will determine the amount within the first three minutes of feeding.

Ensure that the water temperature is always between 72 -82 degrees Fahrenheit depending on the species.

Replenish the tank regularly with clean water.

Action To Be Taken When Cory Catfish Is Laying On Its Side

If you are a cory catfish owner, your instant reaction might be one of panic when you detect your pet fish laying on its side. Often it could just be something trivial like a resting fish. In this instance, it might be advisable to try the following before determining your course of action.


If a cory catfish is laying on its side for an extended period, consider netting to see if it will cause a reaction. No response means that the fish is either sick or dead.

The cory catfish’s instant reaction might be a struggle as they try to break free to swim away.

Tapping On The Tank

Once you have detected a cory catfish laying on its side, tapping on the tank’s glass could result in either a positive or negative reaction.

The noise from tapping on the glass will traditionally gain the fish’s attention, causing some movement.

A dead cory catfish will be motionless, while a sick fish will be lethargic and might continuously topple over or try to hide.


Although cory catfish may take occasional naps of intervals for five to ten minutes per day, it is unlikely that you will see them resting for extended periods. It is worth administering the necessary treatment if you see them laying on their side for longer than 20 minutes.