How to Tell if Your Puffer Fish is Dying? {How Do I Save Them?}

Are you saddened or frustrated that your puffer fish keep dying? Do you want to know how to tell if your puffer fish is dying?

Is it something you did or is there a deeper underlying cause of these deaths?

In this article, we’ll find out why puffer fish die and how we can prevent it.

Why Do My Puffer Fish Keep Dying?

Poor or fluctuating water conditions, unsuitable tankmates and mostly likely the water born illnesses or parasites are killing your puffer fish.

Thankfully, adjustments can be made to help prevent further deaths.

Did A Sickness Kill My Puffer Fish?

The aquarium is a living, breathing ecosystem filled with healthy bacteria and unwanted parasites that can be balanced. Puffer fish are resilient when their immune systems are strong. A stressed puffer fish may end up developing a sickness.

Fungal, viral, parasitical and bacterial diseases can hit your puffer fish all at the same time. You may look for symptoms of one condition or another, but the decline in their health happens so rapidly that they die way too soon.

These diseases will run rampant and become highly transferable between fish in your tank or even before they arrive. The local fish store has to be reputable and able to house disease free fish before selling them to you.

Do Puffer Fish Die When They Puff Up?

Puffer fish are also known as blowfish. They increase in size as a defense mechanism. Puffer fish take in water to bulk up. Their organs shift to their sides and flatten.

The puffing response is due to stress. Some fishkeepers report that constant puffing creates a strain on their organs and makes them more likely to die from organ failure.

Sometimes puffer fish take too long to return to their normal size. The bloating sometimes requires burping. Assisting a puffer fish by gently and momentarily moving them upside down or to their side may relieve some of this pressure so they can return to normal.

What Are Some Symptoms Of A Dying Puffer Fish?

  • Lack of appetite: Puffer fish eat a lot of food happily. Refusing to eat is concerning.
  • Ich: Look for white spots on their gills making it harder for puffer fish to breathe.
  • Abnormal abrasions, bumps or body discoloration: Wounds and bruises can easily lead to infections.
  • Floating to the surface: A weakened puffer fish will float up and also gasp for air at the surface.
  • Sinking: A puffer fish may sink to the bottom of the tank and might be too weak to swim.
  • Hiding: A weak puffer fish hides to protect itself from being an easy target for predators.
  • Puffing up too much: Puffing and increasing in size is stressful and could damage their organs.
  • Swollen gills: Inflammation makes it harder to breathe.

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Did My New Tank Kill My Puffer Fish?

New tanks must be cycled to promote a healthy balance of bacteria. Ammonia levels can get out of control in a new tank. You may see levels of ammonia at 0 and suddenly it rises in a matter of hours.

A tank that is not fully cycled is harmful to puffer fish. The water should not be  foggy or hazy. Please refer to cycling tips and research before placing your puffer fish in a new tank that is not ready for it.

What Are Some Parasites and Infections That Kill Puffer Fish?

  • Anchor worms: Greenish, white or red appearing due to injury
  • Black spots: Look for black speckles.
  • Ich: Look for white spots.
  • Oodinium: Look for tiny yellow or gold spots.
  • Pop eye: Flanges in the eye
  • Fin rot: White, tattered fins
  • Dropsy: Loss of appetite
  • Hole In The Head (HITH): Look for small holes on the head of your puffer fish.

Are There Any Other Causes For The Death Of My Puffer Fish?

It is not fair to you or this article to take on the role of a doctor or vet. The task is on you to be a careful observer. Look and investigate closely. There are many questions to ask you, but a vet or a professional at your service will help much more than internet research.

We do the best we can in this medium because we truly care. Here are other causes for the death of puffer fish.

  • Septicemia
  • Fungus
  • Lice
  • Clamped Fin
  • Skin Flukes
  • Red or White Sores
  • Mycological pollution

What Are Some Tips To Prevent the Death Of Puffer Fish?

These illnesses and infections can be prevented with diligent work to keep the best possible aquarium ecosystem for our puffer fish.

  1. A pH balance at 7.0-7.6 with temperatures at 74°-78°F are ideal.
  2. Keep ammonia levels at 0.
  3. Plant live plants and leave crevices or hiding spaces with plenty of room to move around.
  4. Add more vitamins to their meals by soaking live or frozen food in vitamin based solutions.
  5. Change the water every week at 25% or more.
  6. Test your water quality weekly.
  7. Make sure the filtration system is functional and optimal.
  8. Get a quarantine tank to separate your sick puffer fish from the main tank.
  9. Cycle your main tank first before adding new fish.
  10. Follow the instructions carefully if using medication.
  11. Make sure they are excreting their waste regularly. Peas help pass impacted waste.
  12. Puffer fish like to live alone with large tanks. Consider a larger tank.
  13. Fast and small tankmates that don’t get near your puffer fish work well. No tankmates are better.


The lists in this article are full of reasons why your puffer fish keep dying. We hope the information in this article helps to shine more light on the multiple reasons why your puffer fish died, but more importantly, the tips we have listed at the end can hopefully prevent future deaths.

We wish you and your puffer fish the very best.

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.