Why Black Molly Has White Fungus on Them? {6 Reasons Explained}

Does your black molly have white fungus?

It makes me cringe and I blame myself for it, but I need to know what I did wrong.

In this article, I will cover everything related to why black Molly has white fungus on them?

Why Black Molly Has White Fungus on Them?

The most likely reason for white fungus on your molly is due to a disease. Other reasons include:

  • poor water conditions
  • open wounds or injuries
  • overfeeding
  • nutritional deficiencies
  • weak immunity

I would recommend that you test the water quality first by using a tester that is available to buy on Amazon.

Now that you know why black mollies have white fungus on them let’s see how the fungus gets there.

Black Molly Has White Fungus on Them

Why Do Black Mollies Turn White?

Black mollies may turn white from aging or a white fungal growth. The white fungus appears on black mollies as white cotton-like patches on their:

  • mouth
  • eyes
  • scales
  • fins

The fungus can get there due to various reasons. In most cases, you face fungal outbreaks in the water tank of your mollies because the tank offers preferable conditions for the fungus to grow.

Check out this article I wrote about fungus in the aquarium and what you need to do about it.

White Fungus Causes

Below are 7 reasons for why white fungus affects black mollies and other aquatic life:

1. Unclean Water

Unclean water is the primary reason for the growth of white fungus in the water tank. You can test the water quality by using a tester that is available to buy on Amazon

2. Uneaten and Rotten Food

Overfeeding your black mollies might result in a water tank filled with uneaten food.

If you don’t clean the water regularly, there are high chances of fungal growth on the rotten and decomposed food. Since fungal infection spreads like fire, your black mollies get it too.

3. Decorations Used

Another way the fungus gets in the tank and starts appearing on black mollies is because of the decorations used in the water tank.

The fungus can grow quickly on dead and decomposed plants, gravel, and wood items.

4. Open Wounds and Injuries

Black mollies can get white fungus if they have open wounds or injuries. It becomes easier for microorganisms like bacteria, viruses, and fungi to cause infection and grow on the bodies of mollies.

5. New Mollies in the Tank

Sometimes the white fungus enters the tank from new mollies that are added to the tank.

If you don’t quarantine the new mollies, it’s likely that the water tank can get attacked by the white fungus. It is because most sellers don’t keep mollies and other fishes in freshwater.

6. Poor Immunity or Nutrition

Black mollies can get white fungus due to poor nutrition or immunity. If the mollies are not fed properly, handled with care, or kept in a stress-free environment, they are vulnerable to white fungus.

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Are the White Spots on Molly White Fungus?

No. Fuzzy, white, cotton-like big patches on mollies are usually white fungus.

However, small grain-like white spots could also mean bacterial or protozoan infection. The white spots might also indicate a skin infection or molly fish disease, aka ick or ich.

Will White Fungus Make My Mollies Ill?

Yes. The white fungus is dangerous for mollies if not treated timely. You mollies can experience severe health issues like weight loss, eye infection, and digestive problems because of white fungus outbreaks.

In some cases, your mollies might develop other bacterial infections or even die if no treatment is given.

Now that you know that white fungus can make your mollies ill, let’s look at some ways of treating white fungus on mollies in the next section.

How to Treat White Fungus on Molly?

Are you looking for ways to treat white fungus on mollies? If yes, we are here for you. Follow the given tips to treat fungus on Molly:

1. Put the Infected Molly in the Treatment Tank

It’s advisable to isolate the infected molly in a separate treatment tank where you can treat it. Giving your mollies a saltwater bath is a natural and safe way of treating fungus on mollies. Preferably, you should put one tablespoon of salt per 5 gallons of water.

2. Use Anti-fungal Treatment

Purchase an anti-fungal treatment from a pet supply shop to treat the fungus on mollies. You can also use Methylene Blue or Hydrogen Peroxide to treat white fungus on Mollies. Alternatively, you can also treat the tank water with vinegar to prevent the white fungus from spreading.

3. Take Care of Nutrition

Feeding your mollies properly is another way to ensure that they recover from the fungal infection quickly. A strong immunity system is required for mollies to fight back the white fungus.

4. Visit a Vet

In case of severe fungal infection, consult a nearby vet to seek help. The vet can recommend you proper medication for your mollies.

How to Prevent White Fungus in Fish Tank?

Take the following measures to prevent white fungus in fish tanks.

1. Clean the Water Tank Regularly

It’s essential to keep the water tank clean to avoid the growth of white fungus. An unclean water tank can lead to the development of white fungus. Make sure you clean the water tank properly with a cloth once a week to keep it free from dust, dirt, and other impurities.

2. Maintain Optimum Water Conditions

Run regular water checks to ensure optimum water conditions for your mollies. Ideally, the water temperature for mollies should be 68-82 Fahrenheit with a 7-8 pH level and 0ppm ammonia level. White fungus grows fast in low water temperatures, and a low water temperature is also not suitable for mollies.

3. Change Water Frequently

Try changing 25-50% of the water in the tank twice or thrice a week. You can also try changing 10% of the tank water every day to maintain clean and fresh water.

4. Clean Tank Accessories/Decor

You should adequately wash tank accessories like plants and gravel twice a week to prevent the growth of white fungus.

5. Clean Water Filters

Get in the habit of cleaning the tank’s water filters weekly or monthly to ensure proper flow of air and cleanliness.

6. Avoid Overfeeding

If you notice a lot of uneaten food in the tank, try not to overfeed your mollies. Leftover or uneaten food makes it easier for bacteria and fungi to breed.

7. Avoid Introducing New Mollies Without Quarantining Them

Avoid putting new mollies directly in the water tank that already has mollies. It’s advisable to first quarantine new mollies for a month before introducing them to the common tank.


White fungus on black mollies can be prevented and treated.

Give your mollies a nutritious food and a well-cycled aquarium to give them an immune boost.

Regular tank cleaning, caution when adding new species or decorations, and avoiding putting your fish in stressful situations are all important.

Thanks for visiting HelpUsFish.com for this article. Check out our home page and search bar with hundreds of aquatic or marine life articles to choose from. Bye for now!


Hello, I'm Jason. I'm the guy behind HelpUsFish.com. I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.