White Spots on Fish – How to Treat Ich Disease?

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In today’s article, we’ll talk about a very common problem that appears on many different fish breeds: Ich. First of all, I will tell you what Ich is. After that, you’ll learn more details about it, like how to identify it in the tank and how to treat it effectively.

What is Ich?

Ich is a disease that is very common in personal aquariums. The true name of the disease is Ichthyophthirius multifiliis, which is basically a skin infection. In simple terms, it’s mostly called the white spot disease. What does it do more exactly?

In most cases, Ich will affect your fish, by making them stressed out, and lose their health pretty quickly. Many people think that ich is just a simple disease that is easy to overcome. In some ways that’s true.

However, in this article we’ll find out a little more about this disease, and you’ll see just how serious it is for your freshwater fish. First of all, we should find out how does it reproduce and what its lifecycle is, to be able to measure its impact on your environment:

Ich Lifecycle and Reproduction

Ich Lifecycle and Reproduction

Ich Lifecycle and Reproduction (sourceCC BY-SA 4.0)

Now, let’s talk about how Ich can form in your fish tank. You should know that Ich is a ciliate parasite, that will develop itself in 3 stages:

  1. As a parasitic trophont
  2. As a reproductive tomont
  3. As an infective theront

These terms might sound difficult, but bear with me. I’ll explain each of them right now, so you’ll get the full picture in this matter.

The first stage, the parasitic trophont, appears completely within the host fish’s body. This parasite causes tissue damage, and eventually it leads to the host’s death. Since your fish is the host for the parasite, it grants the parasite all the necessary substances for it to grow and reproduce in a matter of days.

When the trophont matures, it leaves your fish, and it’s going to attach itself to the bottom of the aquarium, where it becomes a reproductive tomont. The tomont appears due to a protective cyst wall, that the Ich produces when it reaches the bottom of the fish tank.

Each tomont cell will undergo multiple division cycles, giving birth to hundreds of theronts, in the time of a single cyst. Once the theronts mature enough, they find their way out of the cyst and will swim around freely in the tank, and look for fish.

When they find free fish that they can attach themselves to, they won’t hesitate. However, if they don’t find a suitable fish, they will die without a host in 2 or 3 days.

If they find the perfect specimen though, they will attach themselves to its skin, and become the Ich disease that manifests itself in white spots.

This is how Ich undergoes its reproduction cycle (in a nutshell).

Now, how can you identify Ich in your personal tank? This is a question that rightfully needs and answer, otherwise, you might not be able to save your fish from this disease.

Identifying Ich in Your Aquarium

Identifying Ich Disease in Your Aquarium

Identifying Ich Disease in Your Aquarium

As you can probably tell by now, the most evident symptoms of this disease, are the white spots that will appear on the infected fish.

Usually, these white spots can appear on your fish’s whole body, however, there are certain cases when they only appear on the gills. What is another symptom?

Due to being infected with Ich, your fish will become much more irritated, and will try to rub themselves against certain objects present in your tank, or against the aquarium wall directly.

As the disease progresses, it will cause other symptoms as well:

  • Severe agitation
  • Loss of appetite (a most common symptom)
  • Respiratory distress

If you notice any of these symptoms manifest in your fish community, you should seriously check your fish for possessing Ich.

If you want to take care of this disease in its early stages, you can identify it by scraping a lesion, and putting it under microscope. What should you notice?

In most cases, a rather large cyst should be seen, that is between 0.5 and 1.5 mm in diameter. Also, you’ll notice a horseshoe-shaped large nucleus in inside it.

This cyst will clearly tell you that Ich has already begun spreading in your tank, and you should take precautions to eradicate it.

Will Ich Kill You Fish?

Unfortunately, the sad answer is Yes. At least, if you don’t treat them in time. As you could probably notice, I mentioned above that Ich can lead to the host’s death, which means that any host fish could die, if not treated in time.

Actually, Ich is among the most common fish diseases, that cause a large number of deaths in personal aquariums. That is because of the misconception that Ich is not a serious disease. However, that is not true by any means.

If you won’t do anything, the fish that show signs of Ich infection, will probably die. It’s just a matter of time.

So, what can you personally do to prevent such an outcome?

Treating White Spots on Fish

Treating White Spots on Fish

Treating White Spots on Fish

In the treatment process, temperature plays a crucial role. Why is that?

Because Ich reproduction is highly dependent on your water temperature. Usually, the disease needs a temperature between 72 and 77 degrees Fahrenheit, to reproduce quickly. So, what should you do?

If your fish can tolerate the temperature, you should heat your tank up to 86 degrees, because the Ich lifecycle will finish much faster. Also, don’t forget that we need to clean the tank from the disease, so it won’t come back.

But to get rid of the disease in its entirety, this is what you should do:

  1. Raise the temperature slowly to about 86 degrees, as mentioned above. Since, the theronts can only live up to 3 days, without attaching themselves to a host, the higher water temperature will assist in killing the disease in 3 days at most.
  2. Remove your fish from the tank, while this process is still happening. During the whole process, your fish must be kept out of the tank, in another aquarium that is free of this disease.
  3. Increase the oxygenation in the tank, in which you keep your fish while the process takes place. By doing this, you can improve their immune system, and give them a better chance at overcoming the white spots.
  4. To make the process more efficient, add salt to your infected aquarium. This will increase the effectiveness of the treatment.

Keep in mind that treating the white spots on your fish directly, can only be done in its early stages. When the disease reached the 3rd stage that I talked about above, you can’t treat it.

Because of this, you must prevent it from ever happening in the first place. How can you do that? Let’s see!

Prevent Ich in Your Fish Tank

Prevent Ich in Your Fish Tank

Prevent Ich in Your Fish Tank

To prevent white spots on fish from ever appearing in your aquarium, you should consider the following steps/methods of prevention:

  • Purchase healthy fish from the get go. If the fish you want to buy present any sign of disease, don’t buy them. Also, never buy fish from a tank that already contains other dead fish.
  • Don’t ever buy plants, which were previously kept in a tank with fish in it. Always keep your newly purchased plants in quarantine for at least 4-7 days, before adding them into your aquarium.
  • Also, don’t ever put your newly bought fish directly in your aquarium, even if you bought them from a safe source. Keep them in quarantine for 2 weeks, to make sure you notice any problems that could surface.
  • If a fish shows any symptom for Ich, remove it to a quarantine tank, and begin treating it as quickly as possible.
  • Keep your eye on the water temperature, pH level and ammonia levels, because fluctuation in these levels can cause an Ich outbreak in your tank.
  • Don’t put too many specimens in your tank. This can cause Ich, and other diseases as well.
  • Do regular water changes, and keep your water at a quality state for your fish community.


All in all, Ich or the white spot disease is among the most common diseases appearing in freshwater aquariums. As you can see from above, it can easily become a deadly plague, so preventing it, is the best way to keep your fish healthy.

I mentioned multiple steps that you need to take, in order to make sure, Ich will never appear in your aquarium. Be careful, and follow each of these steps. They aren’t complicated, or only for veteran fish keepers.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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