How to Treat Fungal Infections in Your Aquarium Fish

Beautiful aquarium fish that are colorful and healthy make a stunning display. Still, when your fish picks up a nasty fungal infection, they can quickly develop unsightly lesions and dull colors. If left untreated, your fish will sicken and die. So, what can you use to treat fungal infections in fish? Let’s find out. 

What Are Fungal Infections in Your Aquarium Fish?

Fungi tend to live everywhere, including on your hands! Fungi are even useful to the food industry where we use them as starter cultures, and (along with helpful bacteria) it makes certain lactose products such as yogurt, kefir, and sour cream.

In an aquarium, on the other hand, having fungi present can be harmful to your fish. The usual fungal infections that plague your aquarium fish include:

  • Ick: The white spots caused by Ichthyophthirius multifiliis fungi are among the most common problems in freshwater aquariums. As the name suggests, the ick or white spots appear on the fish’s body.
  • Cotton Fungus: The cotton fungus is a disease characterized by small cotton-like balls that tend to grow on fish fins and their body.
  • Ichthyosporidium sp.: Internal organ diseases are caused by the Ichthyosporidium fungi. The fungus attacks the kidneys and liver of the fish and then spreads throughout the internal organs before forming skin lesions.

To treat these fungal infections, we can use traditional methods such as salty baths, but they often take time and sometimes prove to be ineffective if the infection is too far gone. Pharmaceutical products have gained popularity, with some containing natural materials and compounds while others are loaded with minerals and chemicals to help save your fish’s life.

5 Best Medicines to Treat Fungal Infection in Aquarium Fish

There are a couple of fungal treatment medications on the market, but the most essential factor to help your fish recover is good tank hygiene and catching an infection quickly. The sooner you treat it, the less chance it is fatal or spreads to other healthy fish.  

1. Pimafix from API

Pimafix from API  


API Pimafix contains a 1% concentration of Pimenta racemosa extract (from the West Indies Bay tree), a popular natural antifungal. A treatment is given daily for 5 to 7 days, with a 25% water change recommended on day 7. When used correctly, it is a fast and effective cure.

Pimenta racemosa is age-old, and it’s been used as an antifungal and antiseptic treatment for decades in men’s barber shops, where the peculiar scent became associated with men’s shaving treatments. 

But Pimenta racemosa (aka Bay rum) is more than a simple odor; its antibacterial and antifungal properties make this plant so unique, and by deciding to incorporate it into Pimafix, a great natural treatment was created.

Pimafix Efficacy 

When using a medication, it’s easy to blame the medication for killing fish if the fish had already been sickly. However, Pimafix is known to be effective in resolving fungal issues if used correctly. 

Pimafix is indicated as effective in treating cotton wool disease, white spot disease, fin rot, and more. A treatment cycle will range between 5-7 days, and a water change is recommended to help reduce fungal levels in the tank. 

The main issue comes with beginner aquarists, who lose their patience when the product does not give instant results. No product can cure a disease overnight. The level of infection and the presence of other bacteria all contribute to how quickly the medication works.

Pimafix Fish and Plant Safety

Add 5 milliliters or a teaspoon full per gallon of water in your tank daily for 5-7 consecutive days. Perform a 25% water change on day 7. 


  • Easy to add to a tank 
  • Treats most forms of fungal and bacterial infections
  • Natural active ingredients 
  • Affordably priced


  • It may negatively affect the healthy bacteria in the tank and your fish’s digestive tract.

2. Tetra TB630W Tank Buddies Fungus Clear Tablets

Tetra TB630W Tank Buddies Fungus Clear Tablets  


When treating your tank for fungal infections, it’s great to have a simple treatment method, and these fizzy tablets are perfect for the job. A bonus is that the tablets treat a broad spectrum of fungal infections, so you don’t have to be an expert at diagnosing just what kind of fungal infection your fish have to treat. 

The fizzy tablets are safe for your fish, though it’s best to remove the biological filter and carbon section of the filter before treatment, as the pills will sterilize these. Once the fungi have been treated and your fish have recovered, you can perform a 25% water change, after which you can add the biofilter and charcoal filters back to your filtration system. 

Remember that since these tablets treat fungi and bacterial infections, your tank will be sterilized, so you’d do well to reintroduce helpful bacteria into your tank. If you remove the biological components of your filter, these bacterial colonies will seed other beneficial bacteria colonies in your tank. Otherwise, you may need to purchase a product to reintroduce helpful bacteria in your tank. 

The Jungle Fungus Clear tablets treat various conditions, including dropsy, tailfin, mouth rot, and hemorrhagic septicemia. The tablets also work preventively when used in routine tank maintenance. Secondary infections often plague a fungal infection, but reducing any bacteria in your tank gives your fish a much better chance at recovery.    

Jungle Fungus Clear Tablets Efficacy 

These tablets work pretty effectively, and results are obtained within a few days, depending on the severity of the fungal infections. It’s wise to keep a box on hand, and one tablet treats 10 gallons, and at the price, it’s an affordable solution to fungal problems. 

Inhabitant Safety 

For the safety of your tank occupants, it’s wise to note the active ingredients of all products you use. This fungal treatment’s active ingredient is Nitrofurazone, which is often applied as a topical antibacterial treatment. 

When introducing new fish to your tank, it’s a good idea to quarantine them in a secondary tank with some Nitrofurazone, which helps to remove any bacteria and parasites that may hitch a ride with the new fish. 

Dosage and Treatment 

One tablet of Jungle Fungus Clear is enough to treat 10 gallons of water, so ensure you dose correctly. In extreme cases, doing a follow-up dose seven days after the initial dose, with a 25% water change, is necessary. 

The water turns a luminous lime green, so don’t get a fright when you see this – your fish won’t turn into the Incredible Hulk, but they’ll soon recover from any fungal infections. 

Once all signs of infection are gone, you can do another water change, let your filter kick in, and soon the water will be clear again. 


  • Cost-effective treatment of a broad spectrum of fungal infections
  • Easy to administer 
  • It can be used preventively with new fish in quarantine 
  • Relatively harmless to fish, though overdosing the tank may harm the good bacteria in their gut
  • Prevents secondary infections


  • You need to remove the biological filter components before treatment, and you may need to repopulate the healthy bacterial colonies

Also Read: 20 Home Aquarium Friendly Freshwater Fish Species For Beginners

3. Seachem for External Fungal/Bacterial/Viral Lesions

Seachem for External Fungal/Bacterial/Viral Lesions  


Next up is another popular medication that no aquarist should be without. Like the Jungle Fungus Clear treatment, Seachem’s External Fungal, Bacterial, and Viral Lesion treatment offers broad-spectrum treatment. The liquid treatment is easy to add to your tank, and the dose is relatively low, so a bottle will last you fairly long. 

Seachem treats a wide range of bacterial, fungal, and ectoparasite-related lesions, which makes it an excellent choice for treating topical injuries and scars that form infections, keeping your fish healthy and shiny. 

While the product is filter-safe, removing any chemical filtration components, such as activated charcoal, from your filter is still best to prevent the filter from removing the active ingredients of the treatment. 

The Seachem treatment contains a synergistic blend of fish-protective polymers, aldehydes, and malachite green. These ingredients create a powerful healing treatment for topical infections.  


Seachem is fast-acting, and fish show improvement within a few days with the correct dosage and water changes. 

Inhabitant Safety 

One careful consideration for your tank is removing all invertebrates, crustaceans, corals, or elasmobranchs (sharks and rays), which makes this a better treatment for freshwater tanks.

Dosage and Treatment

The dosage is one capful per 10 gallons of water, and this should be administered daily as long as needed and if your fish show no stress.  


  • Easy to administer
  • Daily treatment may be more potent to treat severe fungal infections
  • Formaldehyde-free for greater safety
  • Cost-effective treatment
  • Can be repeated as needed


  • Not really suitable for saltwater tanks

4. KORDON Copper-AID External Parasite Treatment for Aquarium Fish

KORDON Copper-AID External Parasite Treatment for Aquarium Fish  


When it comes to illness and your prized fish, prevention is always better than cure. Treating your tank to prevent fungal infections in your beautiful fish collection is the best way to ensure you never lose another fish. Kordon Copper-AID is a preventive treatment to ensure your tank remains fungus-free. 

Simply adding the product to your tank as part of your care routine protects your fish from ick, velvet, and ectoparasites like fluke. The liquid is fairly easy to dispense, and you don’t have to perform any water changes. One single monthly dose is all it takes to help prevent nasty fungal infections. 


It’s best to use this product as a preventive measure. Still, if your fish does develop a fungal infection, you’d do better with Pimafix, Jungle Fungus Clear, or Seachem to help you resolve the infection faster. 

With a single monthly treatment, your tank becomes less vulnerable to fungal infection and the spread of external parasites. The active ingredient, copper sulfate, has been proven to remove and kill fungi that infect fish eggs. 

Inhabitant Safety 

The treatment is safe for freshwater and saltwater tanks. There is no need to remove any tank occupants as copper sulfate is also safe for plants, and your planted aquarium may thrive even better with the supplementation. 

Dosage and Treatment 

One cap treats 4 gallons of water, so calculate your dose carefully to help your fish heal. Treatments are administered as a single dose per month, without additional water changes, as there are no side effects to the tank pH or water clarity. 


  • Copper sulfate is a natural ingredient which is safe to use on all types of tanks
  • Single dose for treatment
  • Perfect for quarantine tanks and when introducing a new tank member
  • Nourishes plants


  • Slightly more costly treatment

Also Read: Best Aquarium Guide: Choosing The Best Tank

5. ReefHD Reef Flux Anti-Fungal Treatment

ReefHD Reef Flux Anti-Fungal Treatment  


Our final choice is an antifungal treatment that relies on the healing power of fluconazole to treat fungal infections, limit algae, and reduce harmful elements that could negatively affect your fish’s health. 

Adding one capsule per 10 gallons of water is sufficient to help reduce fungal spores and limit infections. It helps ensure your reef remains healthy by limiting algae and fungal growth. 

Use ReefHD to treat Saprolegnia and Ichthyophonus hoferi infections with your aquarium fish, but note that certain algae species will be affected, including Caulerpa and Bryopsis, which makes the product unsuitable for tanks with a refugium.  


ReefHD is effective in treating fungal infections, and it makes an excellent choice for a hospital tank where fish are quarantined to eliminate any fungal infections. 

Inhabitant Safety 

ReefHD can damage planted tanks that rely on algae to create an ecosystem. For fragile organisms, the use of ReefHD may be too strong. 

Dosage and Treatment 

Dosage is one capsule dissolved in tank water before being added to the sump. The particles will take 1- 2 days to absorb fully, so don’t mind the floating bits. Dissolve one capsule per 10 gallons of water, and after 21 days, perform a 30% water change. 

In case of overdose, administer Purigen. 


  • Single dose for easy administration 
  • Ideally, it is added to a sump
  • Helps in managing algae
  • Fairly expensive per dose


  • Not suitable for tanks with a refugium

Preventing Fungal Infections in Your Tank Fish

Fungal infections can occur very often if the hygiene conditions of the aquarium are not ideal. To maintain a healthy tank with great water parameters, you should:

  • Perform regular water changes to prevent water clouding
  • Remove dead fish or decaying plant material
  • Never overfeed your fish
  • Maintain a healthy pH appropriate to your fish’s requirements
  • Scoop or siphon the substrate to remove any rotting food particles that can foster fungal growth
  • Quarantine new fish before adding to the tank
  • Wash and quarantine new plants before adding them to the tank

Also Read: Types Of Fish Tank Rocks – Aquascaping, Salt-Water, And Natural

In Conclusion

Although there are mixed opinions on which antifungal treatment is best, API Pimafix is an excellent alternative for curing fungal infections. It is a fast and effective cure for fungi in aquariums when used correctly and according to the manufacturer’s instructions. But you can definitely give the other products on our list a go, too.

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