How to Cure Fungus on Aquarium Fish

If your fish has a white- or gray-colored growth on its mouth or body (often with a fluffy texture like cotton), it could have a fungal infection. Stressful or poor water quality can often cause fungal outbreaks. Secondary diseases can quickly develop so it is important to get the problem addressed immediately. We’ll be covering both ways to treat and prevent fungus from recurring in this article.

If you notice any signs of illness, we recommend that you clean the aquarium thoroughly. Before starting treatment, it is important to make sure that the fish’s environment and surroundings are healthy. Clean the glass to see the condition of the fish. Next, use a siphon or vacuum to change the water and vacuum the substrate. You can read this article to learn how to clean an aquarium.

Fungus can often be prevented. The next step is to determine the source of the infection. The source of the problem must be addressed before treatment can begin. If the problem does not stop, then the fungus might return.

What Causes Fungus In Fish?

A common cause of fungal infection is poor water quality. Many betta fish are affected by this disease. This is because their water containers have no heater or filter. Bettas thrive at temperatures of 78-80 degrees Fahrenheit, so they will need a heater to keep them warm in rooms that are below this temperature. Also, it helps to house them in an aquarium that holds at least 5 gallons or more to prevent their waste from quickly fouling the water. It is important to keep your betta healthy by adding live plants to their tank and doing partial water changes.

Fish can also develop fungus due to nutrient deficiencies. Fish need to eat a varied diet in order to stay healthy. Fishing from the same jar of flakes every day is like giving a person only hamburgers every single day. Sure, they can survive, but their bodies probably aren’t in tip top condition. Therefore, make sure to a) provide a wide assortment of foods so that they get all their essential nutrients and b) give them fresh, high-quality foods. Yes, the expiration date on the container may say the food is good for another three years, but every time you open the container, more air and moisture get inside, causing the food to become stale in a matter of months. Splitting the fish into smaller bags can help preserve freshness. Don’t use wet fingers to remove food from the container. This could cause food to turn moldy and can lead to other diseases.

To ensure that your fish get the essential nutrients they need to improve their immune system, eat a wide variety of high-quality food.

Many livebearers who are bred to be fancy guppies and mollies can get fungal infection as soon as they arrive home from their pet store. The reason aquarium fish are less resilient than livebearers is explained in a separate article. These fish are often mass-bred in countries that don’t have enough fresh water. It is more cost-effective to raise them in freshwater and saltwater. Your guppies who have been raised in brackish waters for most of their lives, and then suddenly move to a pure freshwater environment, are often in a weak state. This makes them more susceptible to foreign pathogens such as fungus spores.

End result: eliminate as many stressors as possible. African cichlids should be less likely to be bullied or attacked by other animals. You should vacuum the gravel regularly for bottom dwellers. Keep the water quality high to protect sensitive species. Avoid keeping shy fish around loud TVs, bright lights that create moving shadows, or high traffic areas in your home. You might consider moving elderly animals with weaker immune systems to a “retirement” tank that has less competition and more activity.

How can you get rid of Fungus from Fish?

Maracyn can be used to treat a fish’s mouth if it shows signs of fungus, rot or swelling. Columnaris is a type of bacterial infection that looks like a cottony growth or grayish-white spots around the mouth. This should be treated by an antibiotic. Clean the aquarium thoroughly and get rid of any chemical filtration such as activated carbon or Purigen. Follow the instructions listed by the manufacturer by dosing 1 packet per 10 gallons of water and repeating every 24 hours for 5 days. You should continue the 5-day treatment, even if your symptoms seem to be disappearing. The infection could still exist in the fish’s body.

If the fungus is located elsewhere on the fish’s body, use a combination of Maracyn and Ich-X. Ich-X is a combination of formaldehyde and methanol that are effective against fungal infections. Clean the aquarium thoroughly and get rid of any chemical filtration before you start treatment. If you have a mild fungal infection, use one packet of Maracyn along with 1 tsp Ich-X in 10 gallons. Let the medication sit for one week to ensure that all symptoms disappear. You can use 1 packet Maracyn with 1 tsp Ich-X for 10 gallons of clean water. Repeat the process every 24 hours for five days.

If you don’t have a planted aquarium or you’re able to move your fish into a quarantine tank with only fake decor, salt is a great way to treat both mouth and body fungus. Although any type of regular salt made with sodium chloride can be used (NaCl), for this article we are using rock salt or aquarium salt.

After many years of using salt for medicinal purposes, we have found that most tetras, barbs, danios, African cichlids, livebearers, betta fish, goldfish, shrimp, and even plecos are tolerant of salt. Other fish, such as anchor catfish, are extremely sensitive to salt so they should not be exposed. For fish that can withstand salt treatment, you should start with a low level of 1 tablespoon of salt for every 3 gallons. After one week, the fish should be completely healed. If not, you can gradually reduce the salt by making weekly 30% water changes. If the fungus is still active you will need to increase the salt content. For detailed instructions on how to do this, please continue reading our full article on salt dosing. You can also use salt in conjunction with Ich-X to pack a powerful one-two punch against the fungus.

What about other fungal medicines?

In our experience, herbal remedies are not very effective against fungal infections. Fish that are afflicted by the disease will need stronger medications to protect their lives. After years of working in a fish shop and helping hundreds of customers, we discovered that Maracyn, IchX, and Salt are the best treatments against fish fungus.

While fungal spores may be present in all aquariums, full-blown infections can usually be avoided. The key to boosting your fish’s overall health is to provide the environment that allows them to thrive and provides them with the nutrients and stress-free environment they need.

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