Is My Discus Fish Sleeping or Dying?

Your discus fish is probably dying if it is sitting on its side on the bottom of the tank or swimming upside down. When discus fish are sleeping, they become inactive and they are just floating around in their normal swimming position.

During resting hours, usually, they will float near the bottom of the tank, and they will be quite inactive. In rare cases, they might turn to their side, although that’s not a very frequent behavior.

Discus fish have different sleep patterns than mammals. It’s perfectly normal for you to be concerned, though. Most of the time, the fish will spend their nights sleeping, and they will find themselves on or near the bottom of the tank.

Also, when they sleep, their colors might fade a bit, which might worry some discus fish owners. But in order to really find out if your fish is sleeping or is really dead, you have to consider some other factors as well.

You’ll notice other signs of illness or if the fish are feeling unwell, you will inevitably see other symptoms as well. So don’t worry too much and stay calm, and observe the fish well.

Discus Fish Sleeping Behavior – How do Discus Sleep?

To understand what’s happening with your fish, you must first know how the fish spend their time when they are asleep.

You must know that these fish will normally float around the tank when they are sleeping. Most likely, they will remain near the bottom of the tank, and around plants, where they have some safety while they sleep.

Sometimes, they will also try to find some form of shelter when they’re sleeping so that they can stay safe when they sleep. This could be between rocks, or even near the substrate, under roots, or between leaves, or even between wooden accessories in the tank.

Their sleeping behavior is very different from mammals. When mammals sleep, we can tell quite clearly when that is happening.

You will also see them breathe, while you won’t be able to recognize with fish. We also sleep by lying down, while fish just float around the water, and will not move around too much during this time.

So you need to first understand how these fish to make sure you know the difference of when your discus fish is sleeping and when it is potentially ill or even dead.

Identify Sick Discus Fish

So, you should know the clear difference between an ill discus fish and between a discus fish that’s only sleeping.

When they sleep, they might potentially display some signs of illness. They will start to lose color, and they will have their eyes open, and they will appear lethargic.

But if they live normally during the day, they eat well, and if there are bright and pretty active during the day, then you should not worry too much.

If you’re looking to spot an ill discus fish, then you should observe their behavior during the day.

If you notice any unusual changes during their daily behavior, then you might start to suspect the illness. Observe the fish for the following signs of illness:

  • Unwillingness to eat, not eating at all
  • Lethargic behavior, not moving around too much during the day
  • Overly active or somehow provoked
  • Physical changes, such as color loss, bulging eyes, unusual patterns on their body, swollen belly, changes in appearance
  • Overly aggressive behavior

If you know these signs of illness, then you need to identify them during the day. That’s when you should start worrying about your fish – but stay calm, with some vet help, you’ll be able to save the fish!

Do Discus Fish Sleep Upside Down or On the Side?

Like we’ve mentioned, it’s pretty rare to see the fish sleep on their side or turned upside down. That’s not a normal sleeping pattern, so you should definitely start to worry if that happens.

Normally, the fish sleep in a straight position, they take the position they normally have when they are swimming around the tank.

If you notice the fish sleeping or moving in an angle, or if they are turned upside down, then there’s something potentially very wrong with the fish.

Do Discus Fish Need Light at Night?

No, you should not leave lights on for your discus fish during the night. They need 6-8 hours of darkness a day, which will help them establish a good life rhythm and a good sleep-day cycle.

Keeping the lights on for the entire day, including during the night, is a very bad idea. The fish will get stressed by the lights, they won’t sleep that well, and they might get sick because of it. So you want to avoid that.

Instead, give them 6-8 hours of darkness at night to let them rest nicely and recover well. This is crucial.

Do Discus Fish Sleep During the Days?

The fish don’t sleep during the day, so if you see them like they are sleeping during the day, then there must be something wrong with them.

They won’t sleep when the sun is out, and they won’t float around the bottom of the tank, too. If they are laying on the ground or if they are hiding, then it means something’s off. It might be a health issue, or it might water parameters that are not right.

In any case, you need to take a closer look at the fish if you notice them like this during the day.

It’s certainly not normal to see them asleep or near the bottom during the day, and you should start to look at other symptoms. Take the fish to the vet as soon as possible if you see this happen.

Why is My Discus Fish Not Moving?

Discus fish are not very active animals, but they will swim around all the time during the day. Even at night, when they sleep, they maintain constant swimming. If your discus is not moving, probably have died.

There could be many reasons why your discus fish died, such as poor water quality, low temperature, overfeeding, due to aggressive tank mates, or some diseases. If your discus fish are dying one after another, the problem is very serious and you should take action quickly.


So hopefully, you now know how to tell a dead fish from a fish that’s sleeping. You need to observe other symptoms as well as their behavior before you start panicking. If you notice other signs of illness, consult with your veterinarian as soon as possible.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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