5 Common Reasons Why Goldfish Lay on Their Sides

4 min read

Unfortunately, a goldfish lying on its side is seldom a good sign, and without help, most times, it will die. Goldfish are meant to swim, and one laying on its side indicates a much larger problem with your fish. So what are the most common reasons for this kind of behavior?


Common reasons why goldfish lay on their sides include swim bladder disease, dropsy, constipation, and water chemicals being off. Fish are incredibly fragile and can quickly become sick when environmental factors change. So getting to the bottom of the behavior promptly is essential.

In the rest of this article, I’ll discuss the top reasons goldfish lay on their sides so that you can better diagnose the problem in your fish. So if you want to learn more about these reasons and how to help your goldfish, read on.

1. Swim Bladder Disease

First, swim bladder disease is a common reason goldfish lay on their sides. Unfortunately, this disease is prevalent in pet fish and can be a result of a few different issues, such as:

  • Overeating
  • Improper water temperatures
  • Bacterial infections
  • Parasites
  • Malfunctioning organs
  • Genetic abnormalities

Swim bladder disease isn’t always permanent, so it’s essential to get to the bottom of the problem and begin treatment immediately. Altering your fish’s diet can sometimes resolve the disease. However, consulting a professional is best if you are concerned your fish has this disorder since they sometimes have to remove the air from the goldfish.

goldfishside PetAquariums 5 Common Reasons Why Goldfish Lay on Their Sides

2. Dropsy

Another common reason goldfish lay on their sides is dropsy. Dropsy is typically a symptom of other underlying issues, such as infections or liver problems. So what exactly is dropsy, and why is it so dangerous for goldfish?

Dropsy is an issue where fluid builds up in the fish’s body. The build-up occurs in the skin and body cavity, causing the fish to be heavy and unforgettable. Sadly, dropsy is almost always a death sentence for your goldfish, but there are ways to try to treat the issue.

The symptoms include:

  • Lying on their side
  • Swollen belly
  • Discoloration
  • Loss of appetite
  • Pale feces

The best way to treat this disorder is usually to isolate the fish in its tank without too much decor and rocks. You need to control the fish’s environment and ensure nothing in the old tank was making it sick. Salt can sometimes help. Consult your vet for the best dosage before adding a heaping tablespoon of sea salt to the tank.

Additionally, a vet can prescribe antibiotics which will increase your goldfish’s chance of survival.

3. Constipation

Just like people and other animals, goldfish can also become constipated. Fish mostly fed an over-processed flake or pellet diet are much more likely to become constipated. Freeze-dried foods can also cause constipation. So it’s essential to incorporate variety into your goldfish’s diet.

Fish also benefit from some greens and even live prey so long as it’s given in appropriate amounts. One of the best ways to help a constipated pet goldfish is to give them canned peas. Canned peas are incredibly soft and will help them pass their stools.

4. Bacterial Infection

Bacterial infections are relatively common in aquarium fish like goldfish, and one of the resulting symptoms is often lying on their sides. Bacterial infections occur for several reasons, such as introducing a new fish with another one to the tank or improper water care.

Other signs of a bacterial infection include:

  • A white film on the fish’s body
  • Milky eyes
  • Shredded fins
  • Bleeding
  • Ulcers on the body and in the mouth

Luckily, bacterial infections can be treated relatively easily if caught quickly. Sometimes you need to add some over-the-counter water medication; other times, a vet must prescribe the fish antibiotics.

5. Water Chemicals and Temperature Are Off

Lastly, the water in your tank is often to blame when it comes to a goldfish lying on its side. As I previously stated, fish are delicate, and chemicals or extreme temperatures are often lethal. Even if your tank’s water pH is good at first, it may shift and change later.

sj test kit PetAquariums 5 Common Reasons Why Goldfish Lay on Their Sides

Having a water monitor device or test you can perform is a good idea to prevent a change in water from going unnoticed. If you don’t already have some test strips, I recommend SJ Waves Aquarium Test Kit (available on Amazon). This kit is awesome because it delivers results fast, so you can quickly adjust the tank’s water.

Final Thoughts

The best way to prevent your fish from getting sick due to poor water chemicals or bad temps is to monitor the tank heavily and also set the tank up correctly in the first place. If you want to learn more about the correct setup for a goldfish, I recommend checking out my article What to Know Before Buying an Aquarium.


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Pet Aquariums

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