You are currently viewing 13 Most Common Guppy Diseases, Parasites, and Treatments [2021]

13 Most Common Guppy Diseases, Parasites, and Treatments [2021]

Guppies are one of the most popular fresh water fishes. They are livebearer and generally hardy fishes. These hardy fish don’t get sick much. Although they are affected by only a few diseases. A properly maintained fish tank and an excellent food diet keep guppies healthy enough to fight off most diseases and treatment would be minimum.

1.Velvet / Oodinium

Velvet / Oodinium

Velvet is not a common disease in guppy fish. The body of a sick fish is covered gold colored dot and it is very difficult to recognize in the early stage because the dots are extremely small and hard to see. The disease is highly dangerous and easily spread to all the fish present in the aquarium.

Velvet disease is also known as gold dust or is caused by the parasite Oodinium. The oodinium swims to find a fish and enter through the skin, fins and gills of the fish. The parasite destroy the cells and feeds on the nutrients inside. After feeding and maturing the trophont drops off the fish and form a reproductive cyst, which divides into a couple hundred oodinium that are released into the water of seek hosts. Oodinium present in most commercial aquariums, but only become a problem when the fish are stressed by poor water quality.


  • Fine yellow or rust colored velvety appearance on the skin.
  • Rubbing body against the hard objects.
  • Rapid breathing
  • Loss apetite and weight loss.
  • In advanced stage skin peel off.
  • Lethargic

2. White spot or ich

White Spot or Ich

The white spot disease is also known as ich. This is common disease in fish keeping hobby. This is caused by an ectoparasite( ichthyophthirius multifiliis) and it is very easy to detect. You will notice small white spots on their fins and skin. These parasites spends most of its life within the fish skin, creating white crysts on the skin of fish. Once these crysts are mature they fall down to the substrate and give rise to thousands of new swimming parasites.


  • Small white spots appearing in the fish body.
  • They start rubbing their skin against rock, plants,leaves, or the sides of the aquarium.
  • They will look uncomfortable and have a loss of desire for food.

3. Dropsy


Dropsy is not a common disease in fishes and guppies. It is caused by bacteria and cannot be treated because the bacteria infect the internal organ. This disease is easily transferable, but fish with a strong immune system will not get affected. Mycobacteriosis causes dropsy in very rare cases. If the immune system of the fish is compromised it can lead to serious infection.

The bacteria usually infect the liver or kidney causing the abdomen to become filled with fluid, it cannot expel. Poor water quality, ammonia and nitrite spike, fluctuating water temperature and pH, improper diet, stress ect are the various reasons that affect the immune system of the fish.


  • Swollen belly
  • Loss of appetite
  • Loose and unstructured scales.

4.Rotting fins and tail rot

Rotting fins and tail rot

Rotting fin is a common disease in guppies and caused by both bacteria and fungus. In this disease, fish fins are rotten and damaged. Aggressive tank mates may nip the fin or tail, which is the main cause of this disease.


  • Fin or tail of the guppy may damaged or fall.
  • Fins or tail look discolored.
  • Clotted blood is seen in the edges of the fins.


 Protozoan is a tiny parasite, that is harmful to fishes, but guppies are the most common that gets infected by this parasite. The parasite attaches to the fishes skin and slowly enters the fish body through their muscles. Until reaches the blood stream. To prevent any circumstances from ever happening you need to practice good tank habits. Heated tank will prevent the growth of this parasites and change 50% of water 3 times in a week


  • Labored breathing
  • Gasping at the surface
  • Clamped fins
  • Heavy mucus secretion
  • Rubbing on object in the aquarium

    6.Columnaris & mouth fungus

Columnaris & Mouth Fungus

This infection is look like a fungus, but it is actually caused by bacteria. You have to check the tank regularly because this disease can turn a sever issues if not check on. The disease is generally seen in female guppies, and rarely affect males as well. It can wipe out the whole fish colony in the tank. Early detection is a big key here.


  • A big white area in the fishes mouth, that will give you a warning sign for this disease.
  • The sick fish have trouble swimming because the muscle get paralyzed.
  • The fish will start eating less and less.

7. Popped eyes

Popped Eyes

This disease is caused by a wide range of factors, and it is very hard to treat. This disease can occur due to bad water quality, bacterial infection, dropsy, fungus, tuberculosis, other internal parasites. Pop eye may not be deadly, but it can cause blindness to your fish.


  • Swelling is usually cause by fluid leaking into the area behind the eyeball.
  • The eye can be cloudy or discolored if the corona was raptured.

  8.Swollen gills

Guppies take in water through their mouth and pass it over their gills in order to extract oxygen. They use an organ called a rake to do this process which is similar to the human lungs, and it is very sensitive organ. Swollen gills are commonly caused by ammonia poisoning. Ammonia is highly toxic which is produced from dead fishes, food waste, organic matter and fish waste. Low quantity of ammonia will affect the gills of the fish, in higher quantities, ammonia is deadly.


  • Swollen gills can cause guppies to come to the surface and gasp for air.

9. Red blood spot

Red Blood Spot

The red blood spot on the stomach or body of guppies also caused by ammonia or nitrite poisoning. It is commonly occur in new aquariums. A new aquarium can take more than 5 weeks to be fully cycled. Introduce fish in a new tank, the level of ammonia and nitrite will increase suddenly, because of the lack of beneficial bacteria to transform these compounds into nitrites. Smallest amount of ammonia and nitrites are highly toxic and will cause serious damage in the fish.


  • The fish might appear to be gasping at the surface of the air.
  • Their gills will take on a red color, look like they are bleeding.

10.Swim bladder disorder

Swim Bladder Disorder

This is not common in fishes, because it is not just one disease but it is more like a disorder. There are various reasons responsible for swim bladder disorder. Physical damage, constipation or digestive issues, shock, low water temperature, parasite and bacterial infection, pregnancy and egg binding and problems with the other organs are the different issues.


  • Swimming trouble
  • Lopsided swimming
  • A distended belly
  • They can’t stay in one position
  • They do not eat
  • Lethargy
  • Hiding
  • Clamped fins

11.Haemorrhagic septicemia

Haemorrhagic septicemia  is a deadly infectious fish disease caused by a virus within the blood of guppy, it is also known as Red pest due to the distinct red streaks that appear on the fish. The virus enters the circulatory system and it will travel throughout. The virus cause damage to body tissues, blood vessels, and the heart and also cause internal bleeding. This is serious condition.


  • Lesions on the body.
  • Ulcer and sores will develop.
  • Fins will start rotting.
  • Gills will pale.
  • Bulging eyes.
  • The fish will stop eating.
  • Become dark in color.



This disease is commonly appear in the larval stage. Scoliosis is a deformation of spine. The spine will developed S or C shaped curvature. It can also affect adult fish especially the female guppies. The main reasons of fish scoliosis are inbreeding, bad diet, tank conditions, and hereditary factors.


  • Trouble swimming
  • Weakness
  • The growth rate of the fish is reduced.

13. Tuberculosis


Fish tuberculosis is a common disease in aquarium that are not maintain regularly. The disease is caused by a bacterium called mycobacterium marinum. It is highly communicable disease that can passed on to other fishes. The aquarium without regular water changes, low in oxygen and high in waste products, this condition helps bacteria to grow out of control and spread the disease in the aquarium. Otherwise this happen when the introduction of new members to the tank, that have already been infected with the tuberculosis.


  • Loss of appetite
  • Discoloration
  • Lesions on body
  • Folded fins
  • Protruding eyes
  • Loss of scales

Common treatments

  • Raise the water temperature.
  • Add your medication in the recommended dose.
  • Or add aquarium salt at a rate of 1 teaspoon per gallon.
  • Keep this stage for 4-7 days.
  • Decrease the water temperature slowly back to normal.
  • Perform a big partial water change of about 70%.
  • Separate the sick fish to a hospital/ quarantine tank.


  • Regular maintenance with proper aquarium set up must be done to prevent many diseases from breaking out in fish aquarium.
  • Keep the aquarium water clean at a healthy temperature at all times. This includes regular tank maintenance that means should performing regular partial water changes.
  • Inspect the tank on a daily basis to make sure that everything look healthy.
  • Remove any dead fishes immediately from your tank.
  • Remove any sick fish from the main tank and place it into a hospital tank.
  • Before introducing new fish to the main tank, keep them in a quarantine tank for some days.
  • Feed the fish well, but do not over feed.

Reduce stress

Most diseases of the guppy fish caused by stress. Stress affect fish’s immune system and it leads to fish become weak. Stress can be caused by many factors. Guppies in their natural habitat, they surrounded by plants, tree root, branches, leaves on other hiding places. In aquarium provide the fish with enough hiding places. Live aquarium plants are suitable for this purpose. Overcrowded fish tank is also a reason for stress in fishes.  Do not keep guppies with other aggressive fishes like beta, gourami, angel fishes, barb fish etc, because guppies are peaceful fishes, they might be suffer. Do partial water changes, confirming that the fish introducing into the tank has the right pH range and it is chlorine free. Keep the temperature in a stable condition. 

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