How To Treat Ich On Fish – 6 Prevention Tips and 1 Go To Cure!

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Have you noticed white spots all over your aquarium fish? This is a symptom of ich, and you’re going to need to treat it soon. The good news is that you can solve this problem with the right knowledge and medications, and that’s just what this article is about!

Ich or white spot disease is a very common, and serious freshwater fish parasite. Most fishkeepers will encounter this problem at some time or another. In this article, we’ll cover everything you need to know about how to treat ich on fish (and how to prevent it in the first place).

What You Need To Know (The Facts)

NameIchthyophthirius multifiliis
Common TreatmentsIch medication such as Ich X, Salt, Heat treatment
CausesProtozoan external parasite
Common Symptomssmall white spots on the fish’s skin and fins, rapid breathing, fish scratching and flashing against objects, drooping fins, clenched fins, surface breathing

What Is Ich (Ichthyophthirius multifiliis)

Ich is a common parasite that affects all freshwater fish. This type of parasite is known as a protozoan (single-celled organism) and it can be found in both wild and captive fish. The parasite is surprisingly large, measuring up to a millimeter in length. Ich can multiply very quickly, and without treatment, it tends to result in fish deaths.

Ich is visible on infected fish as small white ‘spots’ on the fish’s skin and fins. These white spots can multiply rapidly, and unfortunately, the disease is quite advanced by the time these spots become visible. The spots tend to stand out more clearly on darker species and can be pretty difficult to detect on white fish.

Sometimes these white spots will not be visible at all if the parasite is only feeding on the gills of the fish. In such cases, you will notice that the gills become swollen and pale. Infected fish can show other symptoms too, such as fish rubbing against the gravel, losing body condition, or they may stop eating.

The Ich Life Cycle

Understanding the life cycle of ich is really important because it is only treatable in certain stages. The life cycle of the ich parasite is temperature-dependent, and it runs through the different stages faster in warmer water. In a heated tropical tank, for example, the parasite can complete the whole cycle in under a week.

Let’s take a look at the 3 stages of the ich lifecycle1:

Freshwater Ich Cycle
Image from University of Kentucky Drawing by Wyvette Williams and Drew Mitchell

Stage 1- Trophont

This is the parasitic stage where ich is visible and most easily detected. At this stage, the parasite is attached to your fish and feeding. It attaches itself to healthy fish by burrowing through their epithelium to feed on the surrounding tissue.

During the trophont stage, ich is visible as small white spots (raised lesions) on the fins and skin. Sometimes ich is confined to the gills of the fish, in which case you will not be able to see any white spots.

Freshwater Ich

The parasite is protected by the slime coat on the fish’s body so unfortunately, it is not treatable with medications during this stage.

Stage 2- Tomont

The tomont is the reproductive stage of ich protozoa. The trophont stops feeding and leaves the host fish when it is mature. At this stage, the tomont protects itself by encasing itself in a sticky, protective capsule.

The protected tomont settles on the substrate or other surface within the aquarium and multiplies within its protective covering. The tomont starts as a single organism, but multiplies into 100-1000 new parasites during this stage!

Unfortunately, the parasites are still not treatable in the tomont stage because they are protected within a cyst.

Stage 3- Theront

Depending on the water temperature, the third stage can begin within just a day or take as long as several weeks. In this stage, the theronts leave the protective cyst and swim free in the water to look for a new host fish to feed on.

They must find a host within 2 to 3 days or they will die. At this stage, the parasite is not protected and can be treated with the appropriate ich medications. The parasite will progress into the trophont stage if the free-swimming theront succeeds in attaching itself to a freshwater fish.

Preventing White Spot Disease In Freshwater Fish

Now that you know how to treat freshwater ich, let’s take a look at how to prevent it from attacking your fish tank. Remember, prevention is always better than cure!

In this section, we’ll take a look at 6 effective strategies to prevent ich in freshwater fish. These strategies are also useful for preventing several other problems in freshwater aquariums.

Let’s get started!

1. Start Early

Ich gets into aquariums on infected fish, live plants, and any other materials that have been in an infected tank, including the water. You can minimize the risk by setting up a planted aquarium a week or more before adding the first fish. This is an important practice anyway to allow your tank to cycle.

By starting early, any ich parasites present on the plants will die because they will not be able to find a host fish in time. Another great way to avoid parasites on live plants is to purchase only tissue culture plants. These plants are parasite free and grown in labs.

2. Buy Smart

Take a good look at all the fish on display at your local fish store. Do any of them show signs of disease or ich? You can save yourself some trouble down the road by selecting healthy fish from the start.

Online shopping has become easier and more accessible to people all over the world, but it makes inspecting the fish a little tricky. Fortunately, trusted online retailers have built a name for themselves by taking great care of their livestock so you don’t need to worry.

Sometimes fish can look perfectly healthy when you first get them but develop symptoms after a few days in your care. That’s why this next step is so important!

3. Quarantine

The most important thing you can do to prevent ich in your aquarium is to quarantine new fish and plants. In cooler water, Ich usually shows up on new fish after 1 to 3 weeks, so go ahead and quarantine your fish for 4 weeks before introducing them to your main tank.

Ich tends to become apparent much faster in water temperatures between 75°F and 83°F so a week or so is usually sufficient to rule out ich in tropical species. Ich is not the only common aquarium disease, however, and some conditions take longer to show up. Ich is also difficult to detect in cases where it is confined to the gills, so a quarantine period of a month is a safer bet.

Treatment is easier if you notice any signs of ich or other illness in your fish during the quarantine period. You can simply treat the fish in the quarantine tank and avoid treating your whole display tank.

Ich is not only present on fish of course. The free-swimming theront stage can be introduced in aquarium water, and the sticky tomont stage can be spread on plants, ornaments, or other items from infected aquariums. Avoid adding any water from another tank directly into your aquarium and leave ornaments and hardscape from other tanks to dry out for a few days before cleaning them thoroughly.

If you want to learn more about quarantine, check out my quarantine post. While the post is marine fish-focused, the same process applies. Freshwater fish are typically not pre-treated though. Usually, observation can work in freshwater tanks because the vast majority of freshwater fish are tank bred now and diseases aren’t as deadly compared to marine tanks.

4. Stick To Aquarium-Safe Products

Avoid introducing any wild collected rocks, gravel, driftwood, or other materials from ponds or other natural water sources. These environments can carry ich and all sorts of other parasites and unwanted organisms.

5. Water Quality

Keeping a clean tank is very important because fish in aquariums with poor water quality will be stressed and have a weakened immune system. This makes them even weaker against fish diseases like ich. Even fish that have been successfully treated for ich will be far more susceptible to secondary infections in low-quality water.

Running a quality aquarium filter that is big enough for your tank and performing regular aquarium maintenance and partial water changes are vital for maintaining high water quality. You will also need to test your water regularly for the presence of ammonia, nitrite, and elevated nitrate levels.

Avoid overstocking your aquarium with too many fish since ich can spread rapidly in overcrowded fish tanks. Too many fish and too much fish food are also common causes of poor water quality.

6. Prevent Stress

Poor quality water and detectable ammonia levels are not the only cause of stress and a compromised immune system. The following other factors will also put your tank inhabitants at higher risk:

  • Improper diet
  • Incorrect water parameters
  • Incorrect tank temperature
  • Too much or too little water flow

How To Treat and How To Cure

Now that you know more about ich, its life cycle, and how to prevent it, you’re ready to learn how to treat this common aquarium fish disease.

White spot disease is not something that will go away on its own, so starting treatment is very important as soon as you notice an ich outbreak. This parasite can multiply rapidly in an infected tank, and unfortunately, you can lose all of your fish if you don’t take the right steps.

Some fish seem to be more resistant to ich than others, but all fish can be affected. Some species, like clown loaches, are particularly prone to attack by this parasite.

Let’s jump right into the best ways to treat freshwater ich.

Which Medication To Use

The Ichthyophthirius multifiliis parasite is sensitive to the following chemicals in its free-swimming theront stage:

  • Malachite green
  • Methylene blue
  • Copper sulfate
  • Formalin
  • Potassium permanganate

There are a number of ich medications on the market today, but one product that has proven itself in the industry is Ich-X from Hikari. Ich-X contains a combination of effective chemicals in a safer but highly effective dose that will not harm sensitive fish or scaleless fish. If you can get your hands on a bottle, I would highly recommend this product!

How To Use Ich X

Let’s take a look at how to use Ich-X to treat ich in your freshwater aquarium.


Ich x should be added to your aquarium at a dose of 5 ml per 10 gallons of aquarium water. The dosage is very important, so do your best to calculate the actual volume of water in your aquarium excluding substrate, ornaments, and other objects that take up space.

This should be repeated every 8-24 hours continuously for at least 3 days after the last signs of ich are visible on your fish.

Treatment is most effective if you can move all of your fish into a quarantine tank. This ensures that any theronts that emerge in your main tank will die off within about 3 days in tropical temperatures because they will not find a host to continue their life cycle.

By moving your fish into a quarantine tank, and following the recommended dosage, you can treat your fish in the shortest possible time.


Treating ich is only possible while the parasite is in its free-swimming theront stage, so a single dose of medication will not solve the problem. Repeat doses are very important, and the length of time between doses will vary depending on the water temperature.

In the warm water of tropical aquariums, the ich life cycle is much faster and you can treat ich with once-daily treatments for 3-5 days.

Treatment of coldwater fish takes much longer because the parasite spends more time in the tomont stage. In cold water, you should space the treatments out to one dose every 3-5 days. A total of 5 doses will be necessary, so treatment time will take 15-25 days in total.

You can speed up the treatment of ich by increasing the water temperature in your tank. This speeds up the life cycle of the ich parasite. In a tropical aquarium, increasing the water temperature to the lower 80s is usually safe for most fish but this method is not suitable for goldfish and other coldwater species.


You can leave your filter on while administering Ich-X, but be sure to remove any activated carbon media from your filter. This is important because activated carbon will absorb the medication and potentially make it less effective.

Water Changes

It takes a little work but you will need to perform a 30% water change just before each dose. Be sure to remove as much organic material and waste from the aquarium as possible with your gravel vacuum. This will help to remove as many tomonts from the tank as possible before they can enter the water column in search of a new host.


Malachite green is a toxic chemical, so safety is very important for both your aquarium fish and yourself. Take precautions to keep this product away from your eyes and skin. The product is also not safe for live plants.

Aquarium Salt & Non-Chemical Treatments

It is possible to treat ich without any chemicals by changing the water temperature in the tank. This method can be very stressful for fish and plants, however, and should never be used on coldwater fish species.

To use this method, slowly increase your water temperature to 90°F and keep it there for 24 hours. Next, turn down the heater to 70°F and maintain this temperature for 48 hours. By repeating this process, the ich should be killed off after 2 weeks or so.

A UV sterilizer can be useful for controlling parasites, as well as other disease-causing organisms in your aquarium. UV sterilizers will not necessarily kill all the ich in your tank but they will help to manage the problem by killing the free-swimming theronts in the water column.

Treatment with aquarium salt (not table salt) also works but this can be risky because some fish and aquarium plants are sensitive to salt.

Frequently Asked Questions

How do I get rid of ick in my fish tank?

The best way to kill ich in most aquariums is to use an ich treatment product like Ich-X. The treatment will take several days with the correct dosages and dosage rates.

What is the best treatment for ick?

There are several treatments that have been used to cure ich in freshwater fish. These involve changes in temperature and chemicals like salt, malachite green, copper sulfate, and formaldehyde. Aquarium products like Ich-X have been formulated to provide safe and effective treatment.

Will ick go away on its own?

Unfortunately, ick does not go away on its own. It can also spread to other fish in the same tank as the disease progresses, so it’s vital to act as soon as you detect this very common disease.

Can a fish survive ick?

Most fish with a healthy immune system can survive ich if it is treated in time. It has been suggested that fish that have survived ich are less susceptible to future outbreaks because they develop an immune response.

How did my fish get ick?

Your fish may have had ich before you got it or it may have been infected by new fish. Adding water, live plants, gravel, or any other object from other aquariums can also introduce freshwater fish ich.

How do you get rid of ick on fish?

Unfortunately, the ich parasite cannot be treated directly while it is visible on your fish. It will only be present on your fish for a few days before beginning the next stage of its life cycle.

Once ich enters the free-swimming stage, it will be sensitive to chemical treatments with products like Ich-X, salt, temperature changes, or a combination of these treatments.


  • Francis-Floyd, R., Pouder, D., & Yanong, R. Ichthyophthirius Multifiliis (White Spot) Infections In Fish. University of Florida, 2018
  • Xu, D. Preventing Ich. Tropical Fish Hobbyist Magazine. 2014
  • Dickerson, Harry W., and D. L. Dawe. “Ichthyophthirius multifiliis and Cryptocaryon irritans (phylum Ciliophora).” Fish diseases and disorders 1 (2006): 116-153.
  • Dickerson, Harry W., P. T. K. Woo, and K. Buchmann. “Ichthyophthirius multifiliis.” Fish Parasites: Pathobiology and Protection, ed. PTK Woo (Wallingford: CABI) (2011): 55-72.

Final Thoughts

White spot disease can be devastating in the home aquarium. The good news is that treating ich is possible with the right knowledge, medications, and techniques. The most important thing you can do is to get started right away and treat ich as soon as you notice it.

Have you cured ich in your aquarium? Tell us about your experiences in the comments below!


  1. My 75 gallon tank got ich an I treated it by adding salt to the water and raising the water temperature to 88 degrees for 4 days. All gone!

  2. I once experience ick in my 90 gal aquarium, so now I add medicine every month to avoid this from happening again, don’t wait till your fish are infected to act accordingly.


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