How To Know If Your Puffer Fish Is Dying – A Detailed Guide

Pufferfish are normally found in Southeast Asia, India, the Amazon basin, the Congo, Nile, and other Africa rivers. The pufferfish are best known for their unique way of protecting themselves from predators. They make themselves inflate or swell up to avoid being eaten by bigger fish. There are approximately 150 species of pufferfish. There are fewer than 30 species that are considered strictly freshwater fish. If you choose to house a pufferfish, there is a lot you need to know. 

The number one sign is their lack of appetite. Pufferfish will eat as much as you can feed them. They have a huge appetite. If they refuse to eat, it is a big sign that something is not right. They may have contracted Ich. They will show white spots, rapid breathing, gasping at the surface, itching against tank objects, and clamped fins.

With so many illnesses that fish can contract this will be our sole focus today. I will give you all of the information possible on sickness and death in pufferfish. I will cover symptoms along with treatment and preventative measures. First I want to provide you with a little more insight into pufferfish. 

Basic Knowledge of Pufferfish

Pufferfish can be found in the ocean, freshwater habitats, and brackish estuaries. They are known to live in tropical and temperate climates. Your pufferfish is going to do best in an aquarium with a pH of 7.0-7.6 and a water temperature between 74-78 degrees. Figure 8 and Green Spotted Pufferfish are two of the most common pufferfish that are kept in freshwater aquariums. 

As with all freshwater aquarium fish you need to have a good filtration system, heater, and do a 10% water change every week or a 25% water change every 2 weeks. Treat your tap water with a water conditioner and dechlorination, before refilling the aquarium, if needed. You want your aquarium to be nicely decorated for your pufferfish.

Caves, overhangs, and grottos provide hiding places and shelter. There will be different behavior, compatibility, a variety of food options, and tank size requirements depending on which species of the pufferfish you choose to have in your aquarium.

Pufferfish illnesses General Symptoms

With such a variety of illnesses, comes a multitude of different symptoms that you should keep an eye out for. If you can catch the illness early enough, depending on what it is, you will be able to save (and cure) your puffer fish. 

Fish are usually active. If your fish is not as active as normal, look for these other symptoms and signs:

  • Abnormality on the fish’s body
  • Floating, sinking or hiding
  • Puffing is a sign of stress
  • Lesions, spots, or abnormal puffiness
  • Red streaks or swollen gills
  • Winded for air at the surface of the tank

Most Common Pufferfish Diseases or Illnesses

Some of the following diseases and infections are because of certain tank conditions and some are caused by other conditions and issues. 

  1. New Tank– this can affect your pufferfish if the ammonia level is too high. You need to make sure you are cycling your tank before you add any fish to a brand new setup. This helps to remove all harmful issues that can arise in a new tank. If your water is hazy, this can harm your pufferfish. 
  1. Parasitical– Anchor worms, black spots, Ich, & Oodinium are just a few parasites that can harm your pufferfish. Anchor worms are a kind of greenish-white and red that will show up because of injury. Black speckles are a symptom of Black Spot Infection.
  1. Bacterial Infections– common bacterial infections are; pop eye, dropsy, fin rot, and hole-in-the-head. If your pufferfish has flanges in the eye, then it is probably Pop Eye Sickness. Massive growth in the abdomen along with loss of appetite is a sign of Dropsy. If your pufferfish has rough, white fins then that will indicate Fin Rot. Small holes around the puffer fish’s head are going to be a clear sign of Hole-in-the-head. 
  1. Pollutions– mycological pollution is a sure sign of decreased immunity due to lack of essential nutrients. Cotton Mouth is the cause of white fungus in the mouth. Rat is a disease that can disturb your fish and cause skin issues. 

A few other illnesses that can occur in freshwater aquarium fish; Septicemia, Fungus, Lice, Clamped Fin, Skin Flukes, and Red or White Sores.

Septicemia A poison brought into the aquarium by another fish. The symptoms of Septicemia are; open sores, bulging eyes, hemorrhaging of the inner organs and skin, gills look bruised, and a distended abdomen. You can get an antibiotic that will make them feel better and ease any pain, but ultimately they are going to pass away. There is no actual cure for this illness.
FungusPoor water quality and large quantities of decomposing material. Often this will occur when fish are in distress due to injury or another illness. Some of the symptoms of fungus are; white or grey growth on the skin and excess mucus. There is a fungal treatment available, usually at the pet store or you can call your vet. If fungus is left untreated it will kill your fish. 
LiceThe presence of insects, stemming from fish being brought in from an outdoor pond. Lice move extremely quickly from one fish to another, so catching it as early as possible is beneficial. The symptoms of lice are; flat brown/green dots that are moving, red spots caused by infection, your fish is restless and agitated and scratching on objects in the tank. Use a parasitic controller in your water to clear up the parasites. Check with your pet store to see which one is the best. 
Clamped FinThis is not a single illness or disease, but a symptom of a number of different illnesses that can plague your pufferfish. You will notice that their fins are folded against their sides and they will also be lethargic. Unfortunately, this is where the guessing game comes in. You will have to watch your fish closely and see if you can figure out what other symptoms they have, in order to treat them properly.
Skin FlukesThese are worm-like parasites that are barely noticeable. Skin flukes occur when you introduce a new fish or plant that is carrying the parasite. The symptoms to watch out for; mucus on the gills, fast breathing, spiderweb-like scrapes, and itching on tank objects. Call a vet for localized treatment. If this is left untreated your fish will eventually die. 
Red or White Sores This is caused by injury, fighting with tank mates, or a small wound that has become septic. Your fish will be lethargic, possibly also have fin rot, and will have open sores that are either red or white. You can buy and use aquarium salt to help their wounds heal, without any real consequences or death. 


Most fish illnesses, infection, and disease is due to stress, poor water conditions, or introducing a fish that is already sick. Regular water changes and a good filtration system will greatly reduce the risk of illness. There are other precautions you can take to help reduce the risk of illness, infection, and disease. 

  • Make sure they are getting the proper vitamins and minerals from the food you are giving to them
  • Do a minimum 25% water change every two weeks
  • Maintain the filtration system (usually done during water changes)
  • Make sure the temperature and the pH level in the tank stay consistent
  • Invest in a small tank, to use as a quarantine tank, just in case anything does occur
  • Remember to cycle your tank before you bring it home and add any species of fish. This removes chlorine and other harmful things that could be in your water that will harm your fish

As I tell you in each and every publication; please do extensive research on the species of fish that you would like to have in a freshwater aquarium. Knowledge is power and can also be a precaution for illness, infection, and disease. If not a precaution, then you will at least know exactly what to look for and what to expect from the species. Then you will be more confident in diagnosing when something is not right with your fish. Giving you extra time to get the medicine (or other treatment supplies) that you may need to save them.

Related Articles

Swim Bladder Disorder in Freshwater Aquarium Fish
Do I Need To Add Salt to My Freshwater Aquarium?
How Many Fish Should You Have In A 40 Gallon Tank


I'm passionate about fish pets and love sharing everything I learn about them.

Recent Posts