How to Cure Ich in Goldfish 101: Complete Guide To Treating Ich (2024)

Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: May 6, 2024
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Ich is a disease common in goldfish that manifests itself as white spots on the fish’s body. If not treated right away, it often results in the death of the fish. As such, swift intervention is key to preserving your fish’s life.

Article Summary

  • Ich is caused by the Ichthyophthirius multifiliis protozoan and affects the fish’s body, fins, and gills.
  • Symptoms of ich in goldfish include small white capsules on the body, clamped fins, lethargy, flashing, loss of appetite, and hiding behavior.
  • Treatment options for ich include raising the water temperature, using non-iodized sea salt or aquarium salt, and using commercial anti-parasitic medications.

However, treating ich can be tricky due to it being a parasite and its complex life process, which means it’s likely to spread to other inhabitants in your aquarium before you have a chance to eradicate it.

Considering all the options for care possible, it can get overwhelming to decide how to go about the problem. If your fish is suffering from ich, read on!

I’ll be explaining how to treat ich in goldfish, including the right medications and prevention methods, to ensure your fish has best the chance of recovery.

What Is Ich?

Clown Loach With Ich
Clown Loach With Ich

Freshwater Ich or white spot disease is an external parasite caused by the Ichthyophthirius multifiliis protozoan which affects your fish’s body, fins, and girls. The tell-tale sign of ich is small white pustules (typically no bigger than 1mm in diameter) appearing on the skin of the fish.


There is also a saltwater version of ich called marine ich, which is caused by a parasitic protozoa known as Cryptocaryon irritans.

About Goldfish Ich

Although goldfish ich is easy to identify as its primary symptom is tiny white capsules on the fish’s body, it can be hard to treat due to the parasite’s complicated life cycle.

I’ll be going into more detail about the life cycle of ich parasites below, so be sure to stick around!

The Life Cycle of Ich

Ich Life Cycle
Ich Life Cycle (Marine Depot)

The entire life cycle of the ich parasite is complex as it has three stages. First is the trophont/feeding stage, second is the tomont/reproductive stage, and last is the tomont/free-swimming stage.

Understanding the life cycle of ich is important as the parasite is immune to medication and treatment in all stages other than the last phase of its life cycle.

Trophont/Feeding Stage

The first stage of the ich parasite is the trophont/feeding stage where the parasite forms under the fish’s skin, destroying the surrounding cells.

The trophont feeds off the body fluids and dead cells of the fish for several days, growing rapidly during the process.

At this phase in the life cycle of ich parasites, medication and treatment is ineffective.

Tomont/Reproductive Stage

Once the trophont has matured and grown in size, it will fall off its host in order to find an object in the aquarium to attach itself to.

After attaching to a surface, the trophont creates a “cocoon” around its body.

The trophont is now referred to as a tomont, and will multiply quickly by dividing itself. This phase is also immune to treatment.

Theront/Free-swimming Stage

The tomont can produce almost one thousand new parasites (tomites).

Within a couple of days, the tomites will break out of their “cocoons” and become free-swimming ich (now called theronts) to seek out new hosts, causing the entire process to repeat again.

Theronts can survive for roughly 1 to 2 days in a tank without finding a host. This is also the stage when medication is at its most effectiveness.


It takes around 1 week to 8 weeks depending on the temperature of the water for the ich parasite to complete its life cycle. At approximately 77 degrees Fahrenheit, the entire life cycle of the parasite is 7 days.

Symptoms/Recognizing the Symptoms of Goldfish Ich

While the main symptom of an ich infestation in freshwater fish is small white capsules appearing on the body, there are a few other signs that infected fish can display. These include clamped fins, lethargy, flashing, (rubbing against decor or objects in the aquarium), loss of appetite, and hiding behavior or lying at the bottom of the tank.

Fish heavily infected with ich may also lose their color and begin gasping at the surface of the water as the parasite establishes itself in the gill covers.

See what ich looks like in the video below…

【Fish disease treatment example】White spot disease (Ich) and fin rot

Ich Disease Causes

Ich disease is caused by the Ichthyophthirius multifiliis protozoan and usually infects fish when their immune system is already weak, whether that’s due to stress, poor water quality, or another illness/disease.

Additionally, ich can be introduced to an aquarium from a new fish or plant carrying the parasite. That’s why it’s crucial you quarantine any new inhabitants or live plants for at least 2 to 4 weeks before adding them to your main tank.

Prognosis for a Goldfish with Ich

The prognosis of a goldfish with ich depends on their overall health and the severity of the infestation. Unfortunately, if left untreated, ich is often fatal and will spread to other residents in your aquarium.

Can a Fish Survive Ich?

With treatment and TLC, fish can survive ich and can even build a temporary immunity to it. However, even fish with a higher resilience to ich can still pass the parasite on to other inhabitants.

Will Ich Go Away on Its Own?

Ich can go away on its own, but only if there are no fish present in the tank. That’s because the parasite, once it is free-swimming, can only survive for a couple of days without a host.

Some fish can overcome mild infections if their immune system is strong enough or has built an immunity to it, but in most cases, you’ll need to treat fish as soon as they show signs of ich to ensure their survival.

How Long Does It Take Ich to Go Away?

With ich treatment, it usually takes around a week to kill white spot disease and see improvement in infected fish. Depending on your chosen treatment, it could take longer to eradicate the parasite.

How to Treat Ich in Goldfish

There are various ways on how to treat ich in goldfish, including raising the water temperature of the fish tank, non-iodized sea salt or aquarium salt, and commercial anti-parasitic medication or ich treatments like malachite green, formaldehyde, and methylene blue.

What Is the Best Ich Treatment?

Fish Medicine and Dropper
Fish Medicine and Dropper

The best treatment to kill ich and excess parasites depends on the strain and severity of the infected aquarium.

What works for some cases and fishkeepers might not work for others!

Personally, I’ve always found success treating infestations by raising the temperature of my tank and using two ich treatments: malachite green and formaldehyde.

Both of these medications can be used together and excel at eliminating most parasites, including new ich protozoa, skin flukes, and gill flukes.

Using a Salt Bath

Aquarium salt can be used as an ich treatment and for many other goldfish diseases as it helps eliminate parasites, fungus, and bacteria from the water, as well as help fish fight off secondary infections.

You can find fish salt at your local pet store or online, but other salt like non-iodized sea salt or table salt that is both free of additives and caking agents can also be used in a pinch.

Salt irritates your goldfish’s slime coat, promoting the growth of helpful mucus that can help repel some parasites and microorganisms from entering your goldfish’s body, as well as protect them from bacterial infection.

Scaleless Fish

However, salt shouldn’t be used on scaleless fish like plecos as they don’t have the added protection that scales provide. Salt treatment should also be avoided in planted tanks or freshwater aquariums with snails.

For mild cases, add a tablespoon of salt per 3 gallons of water. You can either pour salt treatments directly into your tank or dissolve it in a small cup of water beforehand. Keep your goldfish in the solution for around 4 to 5 days.


Moderate cases of white spot disease may need 1 tablespoon of salt for every 2 gallons of water. Keep your fish in the salty tank water for around 10 days. If your fish are displaying more ich parasites after 5 days, you might need to increase the concentration of salt to 1 tablespoon for every gallon of water.

Bear in mind that salt does not evaporate or break down over time. The only way to remove salt is by changing the water in your aquarium. You should only add salt when you perform a water change.

Water Change

For example, if you’re using a salt treatment for a 50-gallon tank with a moderate case of white spot disease, you’ll need 25 tablespoons of salt to begin with.

If you then change out 20% of water (10 gallons), you’ll also need to add 20% of salt (5 tablespoons) to the fresh water in order to reach the same concentration.

Using Goldfish Ich Medication

Anti-parasitic medication is another effective method to treat goldfish ich. The majority of commercial ich medications are either formalin or malachite green, which are the both the most efficient at eliminating ich.

However, copper-based treatments, methylene blue, and baths of sodium chloride, potassium permanganate, and quinine hydrochloride can also be used (not all at once!).

Remove any carbon in your aquarium before adding any medication and always adhere to the manufacturer’s dosage instructions.


Malachite green can stain silicone and decorations to a green tint and may be toxic to some scaleless fish.

If you’re using formalin, make sure it has been recently purchased or opened as it can convert to paraformaldehyde over time, which can be lethal to fish.

A good way to check for this is to look for formation of a white precipitate in the bottle!


It’s also important to note that some medications can kill off small or large portions of beneficial bacteria in your goldfish tank, so you might want to move your fish to a separate (cycled) aquarium before treating them.

Raise Goldfish Tank Temperature

Aquarium Water Bubbles
Aquarium Water

Raising the temperature of your tank using a heater will speed up the life cycle of ich, making it much easier and quicker to treat the infestation. As mentioned earlier, the parasite can only be killed when it is in the theront stage and actively seeking a host.

Over a few days, raise the water temperature to between 78 to 86 degrees Fahrenheit, making sure not to increase the temperature by more than 2 degrees every 12 hours.

Gradual Adjustment

You shouldn’t increase the heat of your aquarium too quickly as a sudden temperature change can shock your goldfish, resulting in stress and even death.

When your water temperature is at the correct warmth, leave it for at least a couple of weeks before gradually decreasing it again.

Oxygen levels decrease as the temperature in the aquarium rises, so make sure you use some extra air stones or bubblers to increase aeration when you raise the temperature in your goldfish tank.

Temperature Tolerance

Healthy goldfish should be able to tolerate temperatures between this range provided the change is done gradually. However, severely sick goldfish may be unable to withstand temperatures this high.

Some cases of ich will be immune to temperatures between 78 to 86 degrees Fahrenheit, so you might need to increase the water temperature to over 90 degrees Fahrenheit.

Extra Tank

However, make sure you move your goldfish and other tank inhabitants to a hospital tank beforehand.

You’ll then be able to increase your main aquarium water without it potentially harming your goldfish. Most strains of ich will die within 48 hours in temperatures over 90 degrees Fahrenheit.

Preventing Future Infections

While treating ich as soon as it appears in goldfish is important, it’s equally as crucial to put in measures to prevent future infections. Below are some tips for preventing goldfish ich and keeping your fish’s immune system as healthy as possible.

Tips for Preventing Goldfish Ich

  • Only buy healthy goldfish and fish don’t show any signs or symptoms of illness/disease.
  • Try to purchase live plants that have been kept in fishless aquariums. Don’t add any pet store water into your tank as it could contain bacteria, fungus, parasites, disease, etc, that could infect your tank.
  • If you buy live plants that have been housed with other fish, sterilize them in a hydrogen peroxide solution. Add 2 to 3ml of 3% hydrogen peroxide to 1 gallon of water) for 5 minutes and wash them thoroughly. Alternatively, you can quarantine live plants for a minimum of 2 weeks.
  • Quarantine new fish for at least 2 to 4 weeks before adding them to your main tank.
  • Maintain good water quality by checking the filtration system and performing water changes on a regular basis. Most goldfish owners change 25% of their water every week.
  • Treat goldfish and other inhabitants as soon as they display symptoms of ich disease and quarantine them if possible.
  • If you own multiple aquariums, wash your hands and arms thoroughly after working on one of them to prevent the spread of bacteria, disease, etc. Use separate equipment for each tank too.
  • Don’t overstock your tank or house your goldfish with incompatible tankmates to prevent stress and a weakened immune system. When selecting tank mates, picking non-aggressive species that will all thrive in the goldfish’s optimal environment is essential.
  • Have a consistent feeding schedule, and make sure to include a variety of high-quality foods in your goldfish’s diet to maintain good health.

Frequently Asked Questions:

How Quickly Does Ich Kill Fish?

If left untreated, fish will usually die within a week or two of contracting ich, especially if they are stressed or have a compromised immune system.

If you notice any ich symptoms like white spots on the skin of the fish, flashing, lying at the bottom of the tank, you should treat your aquarium as soon as possible so your goldfish has the best chance of survival.

Can Ich Affect Humans?

Ich does not affect humans, but it can be spread to other aquariums via wet skin. If you own multiple aquariums, make sure you wash your hands and arms thoroughly after touching one of them to prevent the spread of bacteria and diseases/illnesses to the others.


You should also use separate nets, siphons, buckets, etc so you don’t pass on any diseases to your other tanks.

Final Thoughts

While white spot disease in goldfish can be deadly, it’s usually easy to treat with the right treatment and medication.

If you find your goldfish turning white, it’s important to recognize signs of ich right away. Effective ich treatment includes raising the tank’s temperature to speed up the life cycle of the parasites, fish-safe salt, and commercial ich treatments like malachite green and formalin.

Remember, the parasite is highly resilient to medication in all stages other than the theront phase when it is free-swimming and seeking out a host.

Feel Free To Share!

If you know any fishkeepers or other goldfish owners, be sure to share this post so they know what to do if their fish comes down with ich!

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