Do Fish Sleep Upside Down?

All animals need to rest as it is vital for functioning and survival! Every animal has a different and interesting way of sleeping – from giraffes standing up to sloths sleeping upside down. On the other hand, sleeping upside down is not considered normal for fish but is instead cause for alarm. 

There is much more to know about the peculiar sleeping habits of fish, including some rare fish that live upside down. Lucky for you, you can find all the information in this article below! 

Do Fish Sleep Upside Down?

It is a common misconception that fish sleep upside down. In fact, if a fish appears to be sleeping upside down, this is most likely an indication that something is wrong.

The majority of fish do not sleep upside down. When fish are upside down, they may look asleep due to the lack of movement, but they are not. If a fish is upside down, this is a sign that they are unwell. There are a few reasons a fish may float the wrong way; however, buoyancy issues are the most likely issue for an upside-down fish. 

Fish have a swim bladder that fills with air and helps keep them buoyant in the water. The fish may float sideways or upside down when this swim bladder malfunctions. This damage may be permanent or temporary, so if it happens to your fish, you must watch closely for a day or two. If this issue persists, then the damage is likely permanent. 

How Do Fish Sleep?

Fish need sleep just like every other animal. It is essential so that they stay healthy and function normally. Now that we know fish do not sleep upside down, you are probably wondering how they sleep. 

When fish sleep, they do not lie down but float relatively still near the bottom of the tank. They may appear awake because they will move their body slightly, but they are not. If you want to learn more about how fish sleep check out our article on it here

Do Beta Fish Sleep Upside Down?

It is uncommon for fish to sleep upside down; however, Beta fish have been known to sleep upside down occasionally. 

The normal sleeping habits for a beta fish are floating near the surface of the water or hidden in-between the aquarium greenery. They sleep upright, hovering in one spot with slight movements of the fins for oxygen flow. 

Beta fish do, on occasion, sleep upside down, but this is quite rare. If you see your beta fish sleeping upside down, it is best to pay attention to your fish for a few hours to observe its movements. If your fish comes out of that position, it was just asleep. However, if it remains upside down for an extended period, it may have a swim bladder issue. 

Some signs that your Beta is just sleeping upside down:

  • A light rhythmic movement of the fins 
  • Hovering in one spot 
  • Relaxed body posture 

The main way to identify if your Beta is asleep is to determine if there are any signs of distress or discomfort. A Beta with swim bladder issues will be floating upside down but may appear distressed by moving constantly and flickering their fins in a non-rhymical movement. 

Importantly, Beta’s, who sleep upside down, tend to do this habitually. Therefore, if your fish is doing this out of the ordinary, it could indicate an issue. 

Do Catfish Sleep Upside Down?

Nine times out of ten, it is grim news if you notice your fish upside down in the tank. However, certain catfish species are known to sleep and function upside down. 

The Upside-down Catfish is a species that is given its name due to living permanently in an upside-down position. The Dwarf Upside-down Catfish of the genus Synodontis is the most common upside-down catfish that you will find in home aquariums. 

These catfish sleep and carry about their daily activities in this upside-down position. This position benefits these fish because they can easily access insects, bugs, or food that floats on the water’s surface. They can also graze easily on algae and other microorganisms that collect underneath aquarium plants, rocks, and logs. 

The other types of upside-down catfish that will both sleep and live upside down are:

  • Asian Upside-down Catfish 
  • Spotted Upside-down Catfish
  • Big-nosed Upside-down Catfish
  • False Upside-down Catfish


In conclusion, most fish do not sleep upside down. If a fish is upside down, they most likely have swim-bladder issues resulting in buoyancy problems. Fish usually sleep in an upright position, hovering in one position with a slight movement of the fins or body to provide them with oxygen. A fish that is asleep will have a very slow reaction time, so this is the best way to identify if your fish is sleeping. 

Beta fish have been known, on occasion, to sleep upside down, but if this is not the usual sleeping position of your Beta, then it may have swim-bladder issues. Lastly, the upside-down catfish is one of the few aquarium fish that both sleep and function upside down.