Why Is My Rainbow Shark Swimming Upside Down: Causes, Treatment, and Prevention

There could be a few reasons your rainbow shark is swimming upside down. Usually, it might be because of the fish’s natural behavior. Some sharks swim upside down to avoid predators interested in their prey from below. However, if this behavior lasts for a long time, it might be because of one or more problems. For example, if your fish tank is dirty and overcrowded, it may not have enough room to swim and play.

Common Reasons Why Rainbow Sharks Swim Upside Down

It Likes to Hide, Especially During the First Few Weeks in a New Aquarium

Some sharks, like the rainbow shark, naturally swim upside down to avoid being seen by predators. Once the rainbow shark gets used to its new surroundings and sees no threats nearby, it should usually start swimming again.

If you want your rainbow shark to be more active and playful, try to provide it with plenty of space, clean its tank often, keep the water at a comfortable temperature, and feed it small tidbits that will make it energetic.

It’s Active, but You Don’t See It

If you can’t see your rainbow shark swimming around, it might be because it’s hiding. When a new aquarium is set up or when there are many changes in the water (like during the rainy season), fish may hide to avoid being noticed or picked on.

To get your Rainbow Shark moving again, ensure the tank is clean and its environment comfortable. If that doesn’t work, try giving your shark some small treats like flakes or pellets to increase activity levels gradually.

Tank Water Issues

If your tank water is dirty, stagnant, or has an unpleasant odor, this can affect a rainbow shark’s activity level. For example, a murky environment may prevent the fish from seeing and hunting for food, leading to malnutrition or even death.

To avoid these problems and keep your rainbow shark healthy and happy clean the tank regularly with fresh water, add fresh plants and rocks to create caves, and install a biological filter that cleans the water regularly.

Inability to Feed

If you’re unable to feed your rainbow shark, there might be a few reasons. For example, if the food is stuck in the filter or is too large for the shark to eat comfortably, it may not get enough sustenance. In this case, try smaller chunks of meat or soft foods that can easily pass through the filter.


If your rainbow shark is exhibiting unusual behavior or showing signs of illness, like poor appetite or lethargy, take it to a veterinarian as soon as possible. Some diseases can be fatal if not treated in time.

Speaking of Diseases… What Disease Causes Uncommon Swimming?

A few diseases can cause uncommon swimming behavior in rainbow sharks. For example, white spot syndrome is a deadly disease that affects fish vision and causes them to swim upside down or backward. Other diseases like prolonged constipation and swim bladder disease can also lead to unusual swimming behavior if not treated quickly. So always take your rainbow shark to the vet if you notice any changes in its normal behavior or signs of illness.

One common cause of swim bladder disease in rainbow sharks is poor water quality. Dirty or stagnant tank water can contain high levels of chlorine, damaging the shark’s respiratory system and leading to swimming bladder disease. Regularly changing the water will help keep it clean and healthy.

Additionally, adding fresh plants and rocks to the tank can create caves that provide shade and improve swimming conditions.

Treating Conditions That Cause Swim Bladder Disorder

To treat swim bladder disorder caused by poor water quality, you must regularly clean the tank with fresh water and add fresh plants and rocks to create caves. You will also need to install a biological filter regularly to clean the water.

Treating Constipation

To treat constipation that results in a swim bladder malfunction, you will need to add fluids and fiber to the shark’s diet. For example, try blending softened fruit or vegetable puree with water and adding it directly to the tank.

You can also give the shark small bits of meat or fish as treats. Additionally, you can try using a feeder that dispenses smaller prey items.

Bacterial Swim Bladder Treatment

If bacteria cause the swim bladder disorder, you must take antibiotics to treat the infection. However, consult a veterinarian first, as some antibiotic treatments can be fatal if not used correctly. Additionally, you can try adding salt to the tank to help kill the bacteria.

Bloating From Swallowing Too Much Air

If the swim bladder disorder is caused by excessive bloating, you will need to reduce the amount of air the shark swallows.

To do this, try giving the shark small bits of meat or fish as treats and stop all oral activities for some time. Additionally, you can try using a feeder that dispenses smaller prey items.

Birth Deformation of the Swim Bladder

If the birth deformation of the swim bladder is causing the swim bladder disorder, you will need to have it surgically fixed.

Physical Damage or Injury

If the swim bladder disorder is caused by physical damage or injury, you must have the swimming area repaired or replaced. Additionally, you may need to give the shark daily baths in a saltwater solution to help reduce swelling and itching.

Poor Aquarium Water Quality (High Nitrates)

Poor aquarium water quality (high nitrates) can cause swim bladder disorder. To fix the issue, you will need to change the water and add additional salt to the tank.

Efficient Ways to Prevent Swim Bladder Disorder in the First Place

There is no one-size-fits-all answer to this question, as each shark will require a different approach to prevent swim bladder disorder.

However, some tips that may help include:

  • Providing the shark with plenty of small prey items (such as fish or krill).
  • Keeping water quality and nitrate levels low.
  • Keeping the tank well-lit.

All in all, it is essential to keep a close eye on your rainbow shark and be prepared to make any necessary adjustments to prevent swim bladder disorder. Additionally, make sure to provide your shark with the best possible care in an aquarium environment.