Fungus in fish: types and solutions

Everything you need to know about how to deal with fungus in fish, home remedies to combat it and the symptoms so you know when to sound the alarm.

Fungi are saprophytic organisms belonging to the kingdom Fungi, probably the least known but important microbial decomposers in ecosystems. They occur naturally in naturealthough these fungi increase in size as the amount of decaying organic matter in the environment increases.

They have a fruiting body consisting of hundreds of threads, with the function of reproducing new structures when attacked by an unknown environment, in this case the body of a fish. These threads are called hyphae and once they reach human tissue, they develop very quickly., because in just one or two days you can already see the first symptoms. The worst thing is that the fungal spores continue to multiply in the environment and can affect other fish.

Fungus can be very dangerous for fishFungus can be very dangerous for fish

And the order in which the fungus affects the fish is as follows: the fungus begins the process as if it were a seed. This seed burrows into the fish’s body and penetrates its skin through the development of putative roots. When the fungus is at a later stage, it spreads to the outside of the body., but we must not forget that its roots continue to be located throughout the inside of the animal. Thus, if the process is not stopped, the roots penetrate into the tissues of the fish with irreparable damage, even to the point of destruction.

Their food is dead organic matter found in the aquarium, be it the remains of dirt or food, and even those tissues damaged or destroyed by the fish themselves for numerous reasons. And there are various reasons why fungus can settle in the tissues of this pet’s body, but first of all This may be due to poor hygiene conditions, careless handling that can injure the fish, or unsuitable temperatures..

This problem mainly affects those people who have public aquariums, those who do not take care or precautions when handling fish, and those aquariums that have not been quarantined before introducing new fish. Therefore, if you see white threads or spots, it is most likely a symptom of a fungal disease in your fish. Below is everything you need to know about fungi, how to control them, home remedies for them, and symptoms so you know when to worry:

Types of mushrooms

Most fungi attack fish when their body is weakened., for example, in case of damage to the mucous membrane, wounds and other pathologies. And when the hyphae, that is, what makes up the body of the fungi, penetrate the tissues of the fish, they can cause irreparable harm, including complete destruction. There are more than thirty-five species of fungi that infect fish, which cannot be described in detail in their entirety, so we will focus on the most common:

Genera Saprolegnia and Ahliya.

Without a doubt, it is this type of fungus that most often affects fish living in aquariums. Appears as a result of secondary infections or searching for food, as they survive on dead organic matter, such as dead eggs, although they can parasitize and take advantage of weaker fish.

There are different types of mushrooms that are worth knowing aboutThere are different types of mushrooms that are worth knowing about

Thanks to the formation of cotton wool layers on the fish’s body, we will be able to determine when they are affected. The problem is that the threads of this type of fungus grow both outward and inward, which causes serious harm to the fish’s body. Treatment should begin at the initial stage.

Ichthyosporidium hoferi

This fungus usually affects fish such as cichlids and carp. This is rare but has devastating consequences as the affected fish release spores through their excrement and thus contaminate the rest of the fish and the entire aquarium. In addition, it affects all the internal organs of diseased fish and causes the formation of black or brown cysts up to 2 mm in size. The worst part is that there is no known cure for this type of fungus.


The fungus Branchiomyces sanguinis and the fungus Branchiomyces demigrans are less responsible for attacking the gills of aquarium fish, causing serious damage such as CO2 poisoning. The result is a malfunction of the animal’s vital organs, leading to suffocation on the surface and rapid breathing. The likelihood that fish will survive this type of fungus is low.

Symptoms caused by fungi

Some of the symptoms that we may observe in our pets when affected by fungi are:

The symptoms are very obvious and we must be careful.The symptoms are very obvious and we must be careful.
  • Brown, white or black spots
  • Cotton stains and flakes
  • Eggs with a cotton-like feel
  • Elongated, compact, white threads.
  • We will be able to see the sick fish suffocating on the surface
  • He has trouble breathing and is rubbing different parts of his tiny body.
  • Has reluctance while eating
  • The most obvious symptom is the death of one or even several fish in your aquarium.

So if you notice your pet exhibiting any of these symptoms or changing their attitude and behavior, it is important to act quickly because if you catch it in the first stage of the disease, there may or may not be options. , it is likely that your fish could die within a day or two.

Fungus treatment

Treatment to save our fish from fungi is carried out not only when the fungi have already attached to our pet, but also before. It is important to maintain good hygiene conditions. and check your aquarium regularly to determine the health of your animals. And everything will depend on how quickly you detect common pathologies that occur in fish with fungi.

The first thing you need to do to carry out high-quality treatment is to sterilize the aquarium water, and then clean and disinfect all elements in the aquarium. Apply fungicides carefully to avoid overdosing and causing fish kills.

There are specialized centers that will tell you how to solve the problem.There are specialized centers that will tell you how to solve the problem.

If you don’t dare because you’re afraid or because you don’t know how to do it, You can contact specialized aquarium centers so that you can be prescribed a more precise treatment. What to do based on the symptoms your pet is showing. The most normal thing is that you are advised to use griseofulvin to treat fungi from the Saprolegnia and Ahliya families. It is recommended to dissolve 10 mg/l in aquarium water for 24 or 48 hours.

Home Remedies

Another option is to use home remedies to save or at least improve the life of your fish. So, It is highly recommended to use sea salt to disinfect aquarium elements.. And yes, we are talking about the same salt that is used for cooking, only coarse salt is better, since treating fungus on fish has a high percentage of good results. You just need to leave them for half an hour to an hour in a saturated solution to kill the germs attached to them.

You can also place the infected fish in a net in a large container and add two tablespoons, that is about 10-15 grams of salt tea, to about two liters of water for 5-10 minutes. This salt bath will have to be done every day until you manage to kill the fungus on the fish and we see that they swim without problems.

There are several options for cleaning aquarium water.There are several options for cleaning aquarium water.

Another option is to use green malachite, that is, a green aqueous solution in a ratio of 1/15,000, in which the fish will be immersed for 10 – 30 seconds. If the bath does not work, it is repeated every 2-3 days, not forgetting that the temperature of the bath should be the same as in the aquarium.

Finally, oxygenated water is a good remedy when fish develop strange growths on their fins or scales. A proportion of 175 ml per 10 liters of water will be enough to keep your pet under water for 10–15 minutes.


  • Information : Gather all the necessary information about what type of treatment is required for each type of fish, as well as what type of water to use, feed, temperature, utensils…
  • Good handling : Do not lift or release the animal suddenly to avoid injury.
  • Quarantine : Whenever you get a new fish, you will have to quarantine it for about 3 to 6 weeks. You will have to pour more liters of water into the aquarium per fish than into the final aquarium, that is, you should never pour less water into the aquarium than necessary.
  • Feeding : The products we give must be purchased from specialized stores, and not live products coming from the environment.
  • Cleaning : We must clean and disinfect both the aquarium and its components if we suspect that our fish is sick.

However, it is best if you have the slightest suspicion to take your pet to the vet because he is a specialized person who knows how to notice any discomfort or signs that we might have gone unnoticed.

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