How to Treat Ich in Fish? A Complete Guide

Fishkeeping is a very satisfying and rewarding hobby, but at the same time, it is difficult for a fish keeper to watch its favorite fish getting sick. When it comes to fish ailments, Ich or White Spot Disease is quite common, and it mainly affects tropical freshwater fish.

Even though Ich is quite common, contagious, and can cause a lot of stress to your fish, still treatable and preventable as well. To correctly treat your fish and free your aquarium of Ich, you need to understand the nature and cause of the disease first.

So, we are here to help you and provide you all you need. This article includes everything you need to know about Ich.

Let us take a detailed look at this disease.

What is Ich Disease?

Ich or commonly known as White Spot disease, is a parasitic infection inflicted by Ichthyophthirius multifiliis. In this infection, your fish can experience scattered white spots or wide patches that can slowly progress with time. Moreover, as the name predicts, this condition is accompanied by extreme itching and irritation.

The question arises of how we can identify if the fish is having Ich or any other disease.

How to Identify a Fish with Ich?

Apart from Ich, many other disorders are presented with spot formation on the skin. Thus, the appearance of white spots is not a definite sign of Ich. There is a common sighting in fish named “stress ich” characterized by white spots dispersed on the whole fish body.

Thus, to distinguish white spot disease or Ich, you need to know all the signs and symptoms of Ich. Well, the main difference is that in Ich, the spots are mainly localized to fins, as fins have the thinnest coat of slime over them. Whereas in stress-induced Ich, the spots are scattered on the whole body.

Furthermore, in white spot disease, the spots are progressing every single day at an exponential rate. In contrast, in stress-related Ich, the number of spots remains constant. In addition, loss of appetite increased irritation, and lethargy is frequently seen symptoms.

Thus, the bottom line is frequent white spots, mainly on the fins and rapidly increasing in numbers are your parameters to identify Ich.

Symptoms of Ich Disease in Fish:

It is essential to know the main signs and symptoms of Ich to distinguish it from other disorders and to seek treatment immediately. Following are the classic symptoms of Ich.

  • Extreme lethargy.White spots on gill covers, body, tail, and especially on fins.
  • Respiratory insufficiency, characterized by severe air gasping
  • Irritability and irritation.
  • Scratching and rubbing against aquarium surfaces and substrate
  • Loss of appetite (Anorexia) and rejection of food
  • Advanced ulceration and severe damage to the body and skin
  • Changes in the pattern of movement and disturbances in balance
  • Discoloration and abnormal behavior (isolation)

It is essential to know that not all fish suffering from Ich will demonstrate the above-mentioned symptoms. Mostly it is too late to recognize as there are no visible signs or symptoms to identify. Thus, it is essential to always keep the tank clean to prevent this condition in the first place.

Mild infection of this parasite is usually non-symptomatic, but as it progresses, the signs are more visible, and early treatment is necessary; otherwise, it can affect the whole tank in no time.

Causes of Ich or White Spot Disease:

Well, coming to the most crucial part of the guide is to know how this disease spreads and what are its causes?

As we know that Ich or Ick is a parasitic infection caused by Ichthyophthirius multifiliis” that originally means “the fish louse with many children.” Thus, the name itself indicates that this protozoan reproduces rapidly with a handful of offspring’s leading to an incredibly fast spread of infection.

The primary habitat of the parasite is tropical freshwater bodies in most parts of the world, infecting wild species. Once in an aquarium, they replicate insanely and are very difficult to eradicate.

A fishkeeper must know the life cycle of this parasite to determine their plan of action to eradicate this parasite.

Life Cycle of Ich Protozoan

The life cycle of the Ich parasite progresses in three primary stages. These stages are crucial to their growth and reproduction.

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Mature Trophonts, Host Dependent Stage host:

The very first stage at which the trophonts (mature parasite) penetrates the epithelium of fish. Fins are initially affected as they are more prone due to a lack of slime. This penetration leads to the formation of raised vesicles or spots on fins, bodies, and gills.

This stage is host-dependent, and at this stage, the parasite cannot survive without a host. It stays on the fish’s body, eats through its skin cells, and damages the fish’s skin leading to ulcer formation.

During this time fish experiences, most of the symptoms especially increased irritability.

Tomocyst Development, Independent Host Stage:

After feeding on the fish skin cells for long enough, the parasite reaches its ideal size and breaks out of the skin of the fish. This leads to the formation of an open sore on the fish’s body that is difficult to cure.

Once the parasite is out of the host’s body, it is free-swimming, and it’s time to attach itself to aquarium surfaces, substrate, or plants. They form a gelatinous coat over themselves for protection. This coat or cyst is called Tomocyst.

Inside tomocyst, the parasite replicates swiftly through mitotic division, forming identical daughter cells known as Tomites. Every new generation consists of thousands of tomites. When these tomites reach maturity, they move out of the tomocyst and become free-swimming parasites.

Infective Theront, Completion of Cycle:

The last stage of development includes the search for a new host. Once the theronts (free-living offspring) break free from the tomocyst, they start looking for a new host to get food and protection. If they are unable to find a host, they may die, and the cycle discontinues.

Temperature-Dependent Life Cycle:

Like most of the parasite’s life cycle, Ichthyophthirius multifiliis’slife cycle is also temperature-dependent. High temperature favors the growth and reproduction of parasites, and low-temperature conditions can halt the process making it quite long.

Thus, it has been found that at 80°F to85°F, the parasite’s life cycle is finished in just a week. Whereas at 50°F, the life cycle can take 3-4 weeks or even more for completion. Thus, it is an important measure to lower the temperature to halt the growth and replication of the Ich parasite.

How to Treat Ich or White Spot Disease?

To treat this contagious disease, you need to understand two critical points from the life cycle of the ich parasite.

1. It is nearly impossible to treat or kill the parasite in the first stage of its life cycle. As in the first stage, the parasite is inside the fish body.

2. The two main stages where you can kill the parasite are the 2nd and 3rd stages that are basically free-living, host-independent stages.

3. Lastly, the decreased temperature is one effective way to eradicate the parasite by slowing down its life cycle.

Based on these facts, you can choose your method to eliminate these harmful agents from the aquarium. Some important and beneficial methods of treating ich or white spot disease are mentioned below.

  1. Treatment through Saltwater:

    The high salt content of the water is a proven way to kill parasites and many other organisms. Thus, using non-iodized salt in an appropriate amount can cure your fish and kill the parasite simultaneously.

    It is believed that saltwater cures and soothes damaged skin and is helpful in relieving itchiness. Furthermore, most of the parasites can not survive such high levels of salinity, and their cells shrink due to loss of water. Due to dehydration, the parasites can die; thus, using saltwater at the free-living stage of the parasite is an effective measure.

    Just like any other thing, this method has some cones as well. Most of the freshwater fishes cannot survive elevated salinity and can get sick. Thus, it is important to understand the tolerance of your fish. If your fish cannot withstand saltwater, then avoid using this method.

  2. Treatment through Chemicals:

    Although store-bought chemicals are somewhat effective in eliminating the parasite, yet they are quite hazardous for the fish. Most of the chemical preparations available in the market consist of a mixture of Malachite Green, formaldehyde, methylene blue, potassium permanganate, and copper sulfate. These chemicals are hard on the parasite but even more stressful for the delicate fish.

    Thus, if you are looking for a quick and easy solution, you can go with chemical treatment. While using the chemicals following things should be kept in mind.

    Do not use the medications in the first stage of the cycle; always wait for the parasite to be away from your fish’s body. Thus, this method is effective during the 2nd and 3rd stages.

    Move the fish out into a quarantine tank to protect them from the toxic effects of chemicals.
    Follow the instructions on the medicine pack strictly.

  3. Treatment through Temperature Changes:

    Another method that is quite effective if carried out carefully and correctly. One benefit of this method is that it is applied during the first stage of the parasite’s life cycle.

    Moreover, it is safe for fish, unlike the saltwater and chemical methods. Although it requires lots of work and care, it is worth it if you are successful in eliminating the danger.

    The first thing you need to do is when you realize that your fish is suffering from Ich, having raised white spots, you should increase the temperature. As raised temperature speeds up the life cycle and the parasite will move out of the fish’s body within 2-3 days.

    Next, you can either decrease the temperature to a limit that kills the parasite or clean the aquarium thoroughly. Temperature variations accompanied by the partial water replacement method are proven to be effective.

    One precaution that should be kept in mind is to avoid extreme temperature changes, as drastic temperature changes can put unnecessary stress on your fish.

  4. Treatment through Water Changes:

    Another efficient method to eradicate the Ich parasite from your aquarium is to perform regular water changes. Once the parasite is in the free-swimming stage, you should replace at least 10-15% water every week. In addition, clean the substrate thoroughly with a vacuum by going deep into it as the parasite might be having its tomocysts in the substrate.

    Moreover, clean the decorations as well. This method is safe for the fish, and it helps get rid of this notorious parasite. Furthermore, if you move the fish in a quarantine tank, it’s even better as the stage 3 parasites are always in search of a host. Once they cannot find a host, they will die, rendering your tank parasite-free.

    All the above-mentioned methods are successful in removing the parasite, so now it’s up to you which method suits you and your fish the best.

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Tips to Prevent Ich in Fish:

The best thing to do is to prevent this infection from happening so you will not have to deal with them. This seems impossible, but it is quite possible. The following tips will help prevent Ich infection from ever happening.

Regular Water Changes:

We cannot stress enough that regular water changes are a solution to almost every aquarium problem, and this can prevent several pollutants-borne diseases and infections.

Almost 20-25% water change twice a month with light vacuum cleaning every week can save your tank from a lot of troubles.

Tank Maintenance and Care:

Maintaining suitable parameters, avoiding drastic changes in parameters are vital for aquarium stability. Changes in temperature, pH, water hardness, salinity, fluctuations in the levels of ammonia, nitrate, and nitrates can put your fish under lots of stress.

Thus, keep your tank and filters clean, regularly test water parameters, and do not overfeed your fish.

Avoid Overstocking the Aquarium:

Overcrowding your aquarium is a cause of many infections. The more the fish, the greater will be the waste produced, and more will be the more susceptibility to infections. Moreover, unnecessary crowd puts stress upon the fish and affects its immunity.

Carefully Select New Fish and Plants:

It is important to keep that in mind while getting a new fish or plant that whether it is healthy or not. Any new component in the aquarium can bring unwanted guests like parasites and Bacterias with them. Thus, it is essential to carefully pick your new pet, plant, decorations, or substrate.

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Moreover, it is advised to keep the new fish in a quarantine tank for a week or two. During this time, your fish will manifest the signs or symptoms of any hidden disease. This will prevent other fish from getting infected.

Keep the Sick Fish in a Hospital Tank:

It is crucial to separate any sick fish from the aquarium as soon as possible. Whether or not you are sure about Ich disease, it is vital to separate the fish in case of any disease.

If you notice irritability, disturbance to movement, changes in appetite, or any other visible sign, First and foremost, you need to do is to move the infected fish to a hospital tank and treat it there.

This is recommended as it will save the rest of the fish from getting infected. In case you discover that the infecting agent is in water, then move the healthy fish to a quarantine tank to save them from catching the infection.

Use Biofilters:

The use of biofilters or biological filtration systems is crucial to the maintenance of the aquarium and the health of your fish. Biofilters are a community of nitrifying Bacterias that mainly act to eradicate high levels of ammonia and other toxic agents.

Without the biofilters, your aquarium will be loaded with toxic chemicals in no time. This, in turn, will affect your fish’s health and immunity in the worst way possible, ruining your tank permanently.

Can Ich Re-infect, my Fish?

An interesting thing about the Ich parasite is that it develops immunity in its affected animals. Once infected fish survives this infection, they can develop immunity against the parasites. The infected fish’s immune system develops anti-ich antibodies that are effective against any new theronts attacking the fish.

These antibodies can even immobilize the parasite, rendering them motionless. Thus, there is no chance of Ich re-infection in fish. Nowadays, the serum and mucous of immune fish are being used to spread immunity in other freshwater fishes. So, in the future, immunization will be the best cure and prevention of Ich infection.

Frequently Asked Questions (FAQs)

1. Is Ich Always Present in Aquariums?

Although this question is still not answered by many aquarists and fishkeepers, there is a high chance of this being true. Ich parasite is quite common in freshwater fish and is a cause of hundreds of mortalities every year. Thus, it is crucial to prevent it and treat your fish as soon as possible.
Always keep an eye on any diseased fish and any new addition to the aquarium. In a cautiously developed and well-kept aquarium, there are low chances of the parasite’s existence.

2-Can Ich Parasite Affect Humans?

Here comes the good news that humans are immune to the Ich parasite. We cannot contract this disease, but we can become a carrier. If you had contact with the infected fish or water from that aquarium, your hands might become a source of spreading the infection.

Thus, it is important to carefully wash your hands or any equipment before dealing with any healthy animal.

3-How long can a fish survive with Ich?

Although it is possible to treat and prevent this disease, if left unattended, this parasite can kill your fish in less than a week. An immunologically weak fish living in unhealthy water conditions can contract the infection more rapidly and, if not treated, will die within a day or two.

Thus, early diagnosis and treatment of Ich disease are inevitable for fish’s health and survival.


Ich is definitely one of the most common fish diseases causing a number of mortalities every year, but fortunately, it’s treatable. The best part is that it renders its victim with a gift of immunity upon survival. Thus, it is best to pay attention to the health of your fish and the condition of your aquarium to effectively prevent this infection from occurring.

We hope this article will help you fight and prevent this notorious parasite in the best way possible.

Until then, stay tuned, and best of luck with your aquarium!

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