Guppies Disease

Guppies are beautiful fish that stand out in any aquarium, but they do have a few health issues potential owners need to be aware of. These illnesses can make your happy fish miserable which is why it’s important to keep an eye out for them. 

So, what illnesses do you need to watch for? Unfortunately, this fish is susceptible to a handful of diseases, such as guppy tail rot and guppy mouth rot. While you can cure most of them, if not caught quickly, could be fatal. 

Below you’ll discover more about how you can tell if your guppy might be sick, some common illnesses to watch out for, and how you can keep them healthy. 

What is a Guppy?

A guppy is a fish that is native to South America. This small creature is known for its stunning colors and impressive appetite. It’s also very easy to care for, making it a popular type of fish for aquariums. 

Signs Your Guppy Might Be Sick

If you’re concerned that your guppy might be sick, you can look for a few signs. 

  • Loss of appetite
  • Disorientation 
  • Bulging eyes
  • There is mucus on their body
  • They seem to be having trouble breathing
  • There are sores on their body

Can You Save a Sick Guppy?

It can be very upsetting to learn that your guppy is sick. While there are some diseases that you can’t always treat, the good news is that many can be. However, you need to catch and treat them quickly. 

What Are Common Guppy Fish Diseases?

Unfortunately, guppies are susceptible to quite a few diseases. 

White Spots

Also known as ick on guppies, white spots occur when a protozoan parasite attaches itself to the fish’s body. While they are small, they can cause severe discomfort to your guppy and usually prove to be fatal if not quickly eradicated.


Oodinium, commonly referred to as velvet disease, is caused by a small parasite. If it infects your fish, their skin will start to turn brown with a goldish tint. Over time, the parasite will cause the guppy to be lethargic and stressed. 

Fin or Tail Rot

A common guppy disease is fin or tail rot. This causes the tips of their fin or tail to look discolored and eventually start to decompose. If not stopped, the disease will continue to spread causing the affected fin or tail to fall off. 

Mouth Fungus

This disease is caused by bacteria that makes the edges of your guppy’s mouth turn white. Eventually, these white spots will turn into fluffy pieces which can cause sores. Most of the time, mouth fungus is the result of an open wound or poor living conditions. 

Gill Disease

Gill disease affects a fish’s gills causing them to be filled with bacteria. This can make it hard for the fish to breathe and could cause lesions. 


Columnaris guppy disease, also known as Saddleback disease, is a parasitic infection that is often hard to identify at first but spreads rapidly. This illness can be due to many things, including an overcrowded tank or low oxygen levels. 

This disease can create white spots around the guppy’s scales. Eventually, it will form sores that make it look as if the fish has a saddle on them. Columnaris can spread quickly so it needs to be treated as soon as possible. 

Guppy Gill Flukes

Guppies are also susceptible to gill flukes. This is when a small parasitic worm crawls into the guppy’s gills making them bleed. Because of this, it can make it very difficult for the guppy to breathe. Many guppies will try to hold their fins close to their body to gasp for air or try scraping themselves against a rough surface to remove the worm. 

Guppy Dropsy

Guppy dropsy is an infection that causes the guppy’s liver and kidneys to swell due to a build-up of fluid in them. Over time, this fluid will become too much for their small body to handle and will make their body look very large and bumpy. Eventually, the guppy will start to become discolored and have trouble swimming. 

Popped Eyes

This medical concern is when your fish’s eyes start to swell. This is due to inflammation of the surrounding tissues. Over time, it will make their eyes look as if they have popped out of their head. Unfortunately, popped eyes can be difficult to treat and could eventually cause your fish to go blind. While it can be caused by different illnesses, this condition is mainly due to poor water quality. 

Blood Spot

Another issue your guppy might run into is a blood spot. This problem is usually caused by harmful bacteria that has been introduced by a new fish. If not removed, the bacteria will cause the guppy to get a bright red spot on their body. 

Viral Haemorrhagic Septicaemia

This common guppy disease is often deadly. When it infects a fish, it will spread through its blood. The guppy will then start to experience symptoms such as bulging eyes, paleness, and a loss of appetite. 

How to Treat Fin Rot?

While many guppy diseases are difficult to treat, fin rot can be quickly fixed if caught in time. 

To treat fin rot, you can add some aquarium salt to the water. After lowering the water temperature to about 75 degrees Fahrenheit, add 1 teaspoon of the salt to it. You’ll then want to do a 90% water change each day afterward for no longer than a week. 

If you find that this method doesn’t help, you could instead use medication, such as Ampicillin or Erythromycin. For this method, do a 90% water change every three days and add the correct medication dosage to the water. This should help destroy the fin rot bacteria and encourage new fin growth. 

How Do You Take Care of a Sick Guppy?

Caring for a sick guppy can be time-consuming, but it will help your fish to quickly heal. Below are a few ways you can help them recover faster. 

Add Aquarium Salt

As mentioned above, aquarium salt can be useful at treating many diseases, especially fin rot. Aquarium salt is evaporated sea salt that doesn’t contain additives. It increases the water’s salinity which helps to prevent the spread of pathogens. 

Keep in mind that you don’t want to overdo the aquarium salt. Too much of it can tweak the water’s salinity which could irritate your fish. 

Depending on your guppy’s needs, you’ll need to add aquarium salt at three stages. The first stage is for mild diseases. To do this, you’ll want to put one tablespoon of this salt for every three gallons of water. You can sprinkle it on top of the tank’s water or dissolve it in a small cup of water first. 

The second stage is for medium-level illnesses, especially white spot disease. For this treatment, put one tablespoon of salt for every two gallons of water. 

The last stage is for diseases that aren’t healing or could spread quickly if not treated immediately. To do this, mix one tablespoon of salt for every one gallon of water. This amount will destroy any bacteria. However, you need to be careful to monitor your fish during this stage to ensure the salt doesn’t irritate them. 

Make sure to clean the aquarium out after the treatments. This will prevent the salt from making it difficult for your fish to swim in the water. You’ll need to make sure to do a 30% water change after each treatment. 

Adjust the Tank’s Temperature

Adjusting the tank’s temperature can also be beneficial. It’s believed that warm water can help kill any disease-causing parasites on the fish. By slightly boosting the temperature, it can prevent the parasites from growing.  

Ideally, the water should be at a temperature of 72-82 degrees Fahrenheit. Anything above or below this temperature could stress your guppy and make their condition worse.  

Remove Carbon Filters

It’s also important to remove any carbon filters in the tank. While helpful, they can filter out medications you put into the water preventing your fish from getting enough of them. It will also dilute the solution making it hard for your fish to get the right amount they need for recovery. Ideally, remove the filter until your fish gets better. 

Try to Clean the Tank

You’ll want to do your best to clean the tank as much as you can. This can help remove any algae that might invite bacteria. It can also give your sick fish a more comfortable space to recover in. 

Sometimes bleach might be needed for this job. While some fish owners are hesitant to use this, bleach is often necessary to kill harmful bacteria. For this, you’ll want to use an 8:1 water to bleach solution. Let this mixture sit for no more than 15 minutes in the tank. Once this time has passed, empty the water and let the tank air dry for at least two days before you put the fish back in. 

If you’re nervous about bleach, you could also use vinegar. You’ll want to use a 1:1 vinegar and water solution. You’ll want to pour this mixture into the tank and let it sit for about an hour. Remove the water from the tank and thoroughly rinse off the aquarium and any objects the solution touched. 

Regardless of the option you use, always make sure that you remove your fish from the tank before cleaning it. 

8 Ways to Prevent Guppy Diseases

Consistently Test and Change the Water

It’s crucial that you always test and change the tank’s water if you want to prevent disease. To test your water, you can buy a cheap filter that measures the current water compounds, like nitrate, ammonia, and the pH. If there is a concerning level of them, you want to quickly clean out the tank. If you don’t, you risk the growth of dangerous algae and bacteria in it. 

When changing the water make sure to keep a guppy’s needs in mind. These fish usually enjoy a water pH of 6.8-7.8 and a water hardness of 8-12 dGH. Because they’re tropical fish, they need warm water to live in, so make sure to keep the temperature around 70 degrees Fahrenheit. 

You’ll want to refresh half of the tank water once a week and do a complete clean of the tank every two weeks. 

Feed Them Antibacterial Food

Antibacterial food can help kill any bacteria in your fish’s body and boost their immune system. You can look for pre-made guppy food designed for immune support or give them some fresh fruits and vegetables. Some of the best to feed them include:

  • Bananas
  • Grapes
  • Zucchini
  • Spinach
  • Peas

Keep in mind that these need to be cut up into minuscule pieces or mashed up. This will help the guppy to consume it easier. You’ll also want to go sparingly with fruit. While healthy, it can contain a lot of sugar that could negatively affect your fish. 

You’ll also want to make sure to not overfeed your fish with these items. Too much food could actually irritate their digestive system which could make them sicker. 

Separate Sick Fish From Healthy Ones

Keeping sick fish away from healthy ones is vital. This prevents the healthy ones from catching the disease. 

This process is known as quarantining. The quarantine tank is near the original one, but keeps the fish away from each other to prevent the spread of disease. It will also ensure that your sick fish gets enough medication to heal. 

You’ll need to make sure that this tank mimics the guppy’s regular tank. Otherwise, it will shock them and could cause stress. This will only make their condition worse. 

You need to be diligent in cleaning the quarantine tank. This will ensure your fish stays healthy and that they have a clean space to heal in. 

Lower Their Lights

Sometimes bright lights can stress fish, especially if you turn them on suddenly. Stress won’t only make them act strange but could weaken their immune system. This could make it harder for them to fight off their illness. 

Bright lights can also make the water too hot which could make your fish uncomfortable and have trouble breathing. 

However, keep in mind that too little light could also stress your fish. Because of this, make sure some sunlight or artificial light can reach them. 

For the best light amount, keep a low light burning nearby for a few hours. You might also want to check to see if the light is adjustable in its brightness so you can change it to mimic day and night. 

Replace Filters

You should also make sure to be consistent in replacing the aquarium’s filters. The filters work to remove organisms out of the water that could contaminate it. If the filter isn’t regularly replaced, it can make it harder for the water to stay clean. 

Besides replacing the filters you might also want to replace the entire filtration system. If this system isn’t functioning correctly, it could make it easier for bacteria to grow. 

Some filters to consider are mechanical, biological, and chemical. 


Mechanical filters use a combination of sponges and floss pads to sort through the water. If any impurities are found, the filter will store them in a small container. 


This type of filter uses natural means to filter out bad bacteria. By using beneficial bacteria or filtering plants, your tank will naturally clean itself. 


Chemical filters mainly use activated carbon to clean the water. Any impurities found will stick to the filter. 

Do Daily Inspections

One of the best ways to stop a disease from spreading is to do daily inspections of the fish. By looking at their body, you’ll be able to tell if they’re suffering or are growing lesions. You’ll also want to look around the tank and ensure there isn’t dangerous algae growth. 

In addition to this, make sure to be consistent with water changes and that the aquarium light mimics a natural day/night cycle. This can help keep your guppy happy while preventing the growth of bacteria. 

Prevent Stressful Situations

Many guppy diseases are the result of stress. As mentioned above, if your fish is stressed, it can weaken their immune system. This makes it easier for diseases to strike. To prevent your guppy from being stressed, create a comfortable living environment for them. This includes giving them plenty of places to hide and explore and not crowding the tank with other fish. 

Add a Water Current

This might sound a bit strange, but a slight water current could be helpful for your fish. You can install a small waterhead in the tank to create it. By doing so, it will give your fish a slight workout. This won’t only be a good mental boost for them, but can help them exercise their body. This can improve their immune system so that it better protects them from illnesses. 

If you decide to do this, ensure that the current isn’t too strong and that you shut off it so that it isn’t running constantly. Otherwise, it will wear out your fish. 

Guppies are unfortunately susceptible to many diseases. However, by keeping the tips mentioned above in mind, you can help prevent and treat many of them.