Guppy Fungus (Types, Causes and Remedy)

Dealing with Guppy Fungus

When it comes to various diseases that can affect guppies, one of the common ones is the fungus.

In this post we are going to discuss some common and rare diseases can affect your guppies,

What causes fungus in fish?

  • Fungi induction can be due to substandard water quality or improper water cycling in the tank.
  • Overfeeding fish causes food to rot in the gavel or bottom of the tank and produce fungus.
  • Infected, expired or contaminated food is another cause of fungal growth;
  • Dead or Sick fish for a prolonged period can cause fungus to grow,
  • Live plants or decors in vivariums can sometimes rot in gavel hence, facilitates fungal growth;

Types of Fungal diseases in Guppies

Guppy mouth fungus: Is mouth fungus in fish contagious?

The fungus mainly affects the mouth that is why termed as mouth fungus.usually not contagious but lethal if untreated;

The first thing is making the proper diagnosis of your guppy so that you know what you are treating.

If you notice a small white prominent area around the mouth that prevents fish from closing its mouth.

If your observe the spongy white substance under a microscope you will see alot of moving organisms within it.

What is happening here is that this growth of the fungus prevents the fish from being able to eat & starving to death.

Is columnaris bacterial or fungal? Are they same?

Columnaris or cottonmouth is a fish disease due to Aerobic and Gram-negative, bacteria columnare.

we often mistaken it with a fungal infection.Unlike fungus, It is highly contagious and sometimes fatal.

This growth not only affects the mouth but it eats away the body tissue creating further infections;

How do you identify Guppy fungus? Signs of Guppy Fungus

it is not the lack of food but the water being able to stream through the mouth and out of the gills.

If you are noticing that your guppies seem to be very lethargic and are staying near the surface water.

Then immediately look at them closely to see if they have developed a mouth fungus.

How do you treat Guppy fungus?

How do you get rid of fungus in fish? is there a way to cure it ,the answer is yes with certain antibiotics we can;

If your guppy’s mouth shows signs of fungus or rot, we recommend using Maracyn or Fritz MaracynOxy.

This antibiotic has shown effectiveness against certain gram-negative and gram-positive bacteria.

Crown fungus

This again is another type of fungus that you want to treat quickly.

You may notice a tiny spot on your guppy and small tiny threads radiating upward and outward from it.

It almost looks like a small crown on the head or upper portion on the guppy.

when you look at the rays that are emanating from it, it seems a like a crown;

They can grow about an eighth of an inch long as compared to guppy body before we usually brush them off;

Is crown rot a fungus?

Crown rot is a soil-borne fungal disease that can survive in wet soil indefinitely, it usually affects many plants,

Fin and Tail Fungus

You may see a grey or white area forming around the fins and/or the tail of your guppy and it seems to be giving them problems with their swimming action.

This will usually occur more often when we keep guppies at a temperature that is too cold for them.

Generally speaking, the fungus usually attacks weak guppies and this weakness could be from damage to their skin or gills.

They may have previously had a bacterial problem that was cleared but the bacteria left some lingering damage which has made them prime for a fungus to occur.

Also keeping the water too cold is a big factor  that has to be watched closely.

How do you treat fungal fin rot?

In case of initial rot simply administer standard antibiotics;

If rotting is more spreading out and the fin has holes use anti-fungal medication.

Keep in mind not to mistaken fugal infection with external columnaris as this may be sign for it as well.

Does aquarium salt help fin rot?

Yes, By using clean water and Aquarium Salt in early-stage we can cure fin rot,

Aquarium Salt is an inexpensive and commonly available item in pet stores.

The AQ Sodium chloride present in the salt helps in healing fish wounds and also calm down the fish.

Saprolegnia fungus

What is Saprolegniasis in fish?

Saprolegnia (commanly known as oomycete infection, winter kill or water mold ), is a freshwater fungal pathogen;

It usually appears like a patch on fish’s skin, if unattended or treated may be fatal in many cases.

It is one that affects the fry and juveniles and death can occur before the symptoms even show.

What causes saprolegnia?

Saprolegnia or commonly known as Winter fungus usually infects freshwater fish and their eggs,

saprolegniasis infection typically occurs when the temperature dips below 15°C and then rises in early spring.

How do you treat saprolegnia?

The effective ways to Treat Saprolegnia infection is by medicating the tank water with potassium permanganate.

What is the white fungus on my fish?

White spot disease also known as (ich or ick) is a common freshwater aquatirum ailments induced by pathogen;

The scientific name of the pathogen is ciliate protozoan Ichthyophthirius multifiliis;

White spot or ick usually affects freshwater captive fishes like guppies;

Will fish ick go away by itself? Yes, usually the immune system of fish is strong enough to resist ich and similar pathogens and visible ich or ick will go away on its own in few days;


Your local aquarium shop should have a selection of products to use for you to treat your fish with,

No matter which form of fungus your guppy is dealing with them,

each demand immediate and specific treatment for the actual fungal condition.

but again it is highly important that you are able to identify which fungus you are dealing with,

So that you can assure yourself to get timely and proper line of treatment for your fish.

I hope this article have given you a lot of insight regarding fungal infection in guppies;

You would also like to read about more guppy diseases and how to deal with them?

Which medicine is used for fish fungus?

Formalin in higher concentration can be used to control fungus on fish eggs, while In lower proportions, it kills parasites on guppy gills, fins and skin.

How do you get rid of fungus on fish eggs?

(FDA) approved medicines like Formalin and hydrogen peroxide can be used to treat fungus on eggs.

What temp kills ich or ick?

The sick juveniles or tomites die if the water temperature is at 90°

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