Identify and Treat Freshwater Ich (White Spot Disease)

What is Ich?

White spots on freshwater fish scales from Ich

Ich is one of the most common aquarium diseases.

In fact, Ich is so commonly experienced that many fish keepers believe it to be found in every single aquarium.

So, what is Ich exactly?

To put it simply, Ich is a parasite that appears on the body, fins and gills of fish. If left untreated, Ich will eventually kill your fish.

Ich is easily transferred from one tank to another by fish, invertebrates, plants, decorations or even maintenance equipment like your gravel vacuum or nets.

These parasites are small. Real small. So small, in fact, that you need a microscope to see them…

Freshwater aquarium Ich white spot disease viewed under microscope

If caught early, Ich is very treatable, and many fish make a full recovery.

What makes Ich unique among fish diseases is that it has a life cycle.

1. Parasite stage

The Ich burrows into fish, feeding on the skin and tissue, causing irritation.

As it burrows into the flesh of your fish, it causes a wound. Your fish tries to protect itself and a white, crusty wall seals the Ich in. This wall looks like a white spot.

Many people think the white spot itself is Ich, but it’s actually more like a scab. The Ich hides behind it.

While burrowed beneath the skin, the Ich are protected from any medications you add to your aquarium.

This is the stage when most fish keepers first become aware that their aquarium is infested with Ich – the tell-tale white spots that cover your fish make it easy to identify.

2. Intermediate stage

Once the Ich matures, it bursts through the white crust and floats around looking for a hard surface to attach to – generally the bottom of your aquarium.

The white crust that covers the wound of your fish falls off, leaving an open wound. At this stage, your fish are prone to infection or fungus. Yep, it’s possible for fish to have more than one disease at once.

3. Reproductive stage

Once on the bottom of your tank, the Ich seals itself in a tomont, which is essentially an egg.

Inside the egg, the Ich divides itself into hundreds or even thousands of babies called theronts.

Because the egg is sealed, the babies inside are protected from medication.

4. Infectious stage

When the egg hatches, the theronts are released into the water. They swim around freely, hunting for fish to burrow into.

The babies can only survive for a few days. If they don’t find a fish to infect, they die.

It is during this stage that Ich is vulnerable to medication.

So, how long does all this take?

Well, it all depends on the temperature of your tank.

The higher the temperature, the faster the life cycle.

  • 70˚F (21˚C) – Up to 18 days
  • 85˚F (29˚C) – Up to 6 days

As you see, the temperature of your tank greatly affects the life cycle of Ich. Generally in a tropical tank, the lifecycle generally takes 10 to 12 days. Raising the temperature is one of the tools you can use to rid your tank of Ich.

The following aquarium creatures are generally considered immune to Ich:

  • Invertebrates – e.g., Shrimp
  • Gastropods – e.g., Snails
  • Amphibians – e.g., Frogs
  • Reptiles – e.g., Turtles

However, that doesn’t mean they can’t “carry” an Ich infestation into your freshwater tank. Use a quarantine tank to avoid this!

How does Ich get inside your aquarium?

Gourami with Ich on fins and scales in freshwater aquarium

There are a few topics in fishkeeping that divide the community. How Ich first gets inside your fish tank is one of these debates.

There are two theories as to how Ich first appears…

1. It’s transferred from tank to tank – Ich is highly contagious and easily transferred from tank to tank. It can hitchhike on a newly bought fish, plant or invertebrate when you add it to your aquarium.

2. It’s always in your tank – Ich is so common that many believe that Ich exists in every tank and only infects your fish when conditions are right.

There still has not been 100% agreement among the fishkeeping community as to which argument is correct.

It doesn’t really matter which theory is right!

You see, the methods of identifying, treating and preventing Ich from infecting your fish are still the same.

So, leave the two sides to fight it out over who is right. You just worry about the important things like protecting your fish from Ich.

How do you identify Ich? (Symptoms)

Most fish keepers first identify Ich when their fish breaks out in white spots, randomly scattered across the body, fins and gills. The white specks almost look like someone sprinkled salt over your fish.

At first, it may just be a single spot…

Cardinal tetra with one single white spot on scales the beginning of ich

On its own, a single spot does not confirm that your fish is suffering from Ich. You see, many other diseases such as fungus and columnaris can start out as a white-colored spot.

However, if more and more white spots appear, it’s almost certainly Ich.

Cardinal tetra fish covered in lots of white spots ich

These spots can be seen without magnification and can grow into larger white patches. If untreated, things can get pretty bad…

Cardinal tetra dying from Ich covered in white spots

In the very early stages, these white spots are most noticeable on clear fins.

Close-up on cardinal tetra tail covered in white spots

If your fish has big fins with bright colors, then these white spots can be considerably more difficult to notice.

Betta fish with Ich on his fins

The same goes for fish with spotted patterns…

Cory catfish covered in Ich white spots resting on bottom of aquarium

These spots led to Ich being commonly referred to as white spot disease.

Unfortunately, in some cases, Ich may only be present on the gills and mouth – not on the skin or fins. The bad news is that Ich in these areas is very difficult to identify for someone who has never battled it before.

Fortunately, you can use other symptoms to diagnose your fish as having Ich. These symptoms affect your fish’s behavior.

If Ich establishes itself in the gills, it will make it more difficult for your fish to breathe. Because of this, your fish’s gills will move much faster than normal, as they try harder to breathe.

You may even notice your fish move to the top of your aquarium where there is more oxygen or even gasp for air at the surface of your tank.

As the Ich infestation progresses, your fish will become lazier and move slower than they normally would.

German blue ram with white spots (Ich) hiding behind plant in aquarium

You may even notice your fish lose color. As the infection progresses, fish often refuse to eat.

Scratching is the final clue that your fish has Ich because those white spots can be itchy. Unfortunately, your fish doesn’t have hands to give himself a good scratch. Instead, he will brush against objects to make the itching stop, which can result in scrapes and damaged skin.

While some species of fish are more prone to Ich than others, such as tetra, no fish is immune to it.[3]

I also point out that if you notice Ich on one fish in your tank, then it’s safe to assume that they all have it. Ich generally shows up first on the most sensitive or stressed fish, but due to how contagious Ich is, your other fish already have it. It’s simply too early to identify.

It’s important that you correctly identify Ich and not a disease with similar symptoms. Many Ich treatments do not cure other diseases.

How do you treat Ich?

Golden balloon ram with white spots on fins, Ich

Have you diagnosed your fish with Ich?

Well, the next step is getting rid of it.

This treatment process cures your fish and aquarium of Ich at the same time.

Important: Your fish might already be too weak or too far gone to be saved. While I cannot guarantee the survival of your fish, using these steps will give your finned friend the best shot of overcoming Ich.

1. Check your water quality

Using an aquarium test kit to make sure water quality is good when treating Ich

As with any disease, to see the best results when fighting Ich, you want the water in your tank to be pristine.

You should already be regularly testing your water with a good aquarium test kit. If you aren’t, now is the perfect time to start.

So, grab a test kit and check the following:

  • pH
  • Ammonia
  • Nitrite
  • Nitrate
  • KH
  • GH

Not only will good water quality allow your fish to recover faster, but it can also impact how certain Ich medications affect your fish.

If anything looks out of the ordinary, you want to fix it before moving forward with Ich treatment.

Step 2. Get your fish eating

Tetra infected with Ich covered in white spots eating fish food

Note: If your fish are eating normally, you can skip this step. However, I suggest reading it just in case your fish refuse food in the future.

Many fish that suffer from Ich refuse to eat. Not exactly a good thing when trying to save your fish.

If your fish isn’t eating, she will become weak and less likely to overcome her battle with Ich.

Fortunately, there is a natural solution that gets even the most stubborn fish eating again…


Garlic is used to stimulate appetite, meaning it makes your fish want to eat. It can make all the difference to an Ich-infested fish that refuses to eat.

So, how do you feed your fish garlic?

One popular solution is to swap your fish over to a garlic-infused diet.

Once you beat Ich, swap back to your fish’s usual food – there is no need to feed your fish garlic if they are disease-free.

Alternatively, you could always mix up your own garlic infusion. It’s a little time consuming, but it will save you money. All you need is a medium-sized bulb of garlic.[5]

  1. Peel the garlic and cut the ends off each clove.
  2. Microwave the cloves for 10 seconds.
  3. Cut the cloves lengthwise into thin strips.
  4. Place the strips in a cup of dechlorinated water.
  5. Let sit at room temperature for 12 hours or longer for a stronger solution.

The longer you soak it, the stronger it becomes. This mix can be refrigerated for up to two weeks.

And, there you have it!

As a side note, garlic is a parasite-fighting superfood… And, Ich is a parasite.

However, on its own, feeding your fish garlic won’t rid your tank of Ich. You need to combine it with the next two methods…

Step 3. Raise your aquarium’s temperature

Ich covered Goldfish in aquarium that is too hot looking at aquarium and sweating

Now, you only have a very narrow window when Ich is vulnerable to medication – which is why treating Ich can be so difficult.

The good news?

You can make this window roll around sooner by increasing the temperature of your aquarium. 86˚F (30˚C) is the sweet spot.

Now, the trick is to increase the temperature slowly.

Fish are sensitive to rapid changes in temperature. If you raise it too quickly, you risk killing your fish.

So instead of adjusting the water in your tank straight to 86˚F (30˚C), increase it 2˚F (1˚C) each hour.

Regularly check the water temperature with a good aquarium thermometer to ensure that you are not cooking your fish.

Note: This step is less suitable for overstocked tanks, tanks with poor circulation or heat-sensitive fish. If your tank checks any of these boxes and you don’t feel comfortable increasing the temperature, please skip this step.


Well, as the temperature of your aquarium rises, the water in your tank will hold less oxygen. This is particularly problematic if your tank has poor circulation or is overstocked, where oxygen is already low.

In these cases, raising the temperature may cause problems breathing. Not something you want if Ich has infected the gills of your fish.

Fortunately, this can be overcome by adding an aquarium air pump and airstone or increasing the flow on your filter. This will agitate the surface of your aquarium, improving the amount of oxygen available to your fish.

As for heat-sensitive fish such as goldfish, only adjust the temperature as high as they will tolerate. Any increase in temperature will help shorten the lifecycle of Ich – giving you a better opportunity to get rid of it for good.

Don’t worry, you can still beat Ich without raising the temperature, but it will take a little longer.

Step 4: Choose your Ich medicine

With your fish fed, and the temperature raised, it’s now time to get rid of your Ich problem once and for all.

To do that, all that is left to do is add Ich medication to your tank.

Before adding Ich medicine to your tank, remove any chemical filter media such as activated carbon or Purigen. These chemical filter media can soak up certain types of medication, preventing it from treating your fish.

As always, follow the directions closely when treating and watch your fish like a hawk for the first two hours after adding any medication. If you notice any adverse reactions, do an immediate water change and discontinue use.

Warning: Many beginners kill their fish by overdosing their tank with Ich medication. Ich medication is dosed to the amount of water inside your tank. And, that’s where mistakes are made…

You see, your tank will never actually hold the amount of water it claims. By the time you factor in your substrate, plants, decorations and even fish, there will be considerably less room for water. Please keep this in mind when determining how much Ich medication to add to your tank.

The dangers of Ich and secondary infections

Gourami covered in white spots in later stages of Ich

Fish can catch more than one disease at a time. In fact, by coming down with Ich, your fish is actually more likely to be afflicted with another disease.

Because your fish is already in a weakened state from both stress and Ich, your fish is much more likely to catch other diseases than he normally would.

For example, this platy is suffering from columnaris of the mouth, which came on while being treated for Ich…

Platy with a couple of white spots from Ich and columnaris secondary infection

This is referred to as a secondary infection.

And let me tell you, battling two or more diseases at once sucks. For you and your fish. Not only will you need different types of medication to combat the other diseases, but your fish’s chances of recovery greatly diminish.

This is why it’s so important to get your water quality sorted out in the beginning. See Step 1 of FishLab’s Ich elimination process. It helps reduce the chances of a secondary infection.

It is for this reason that you should monitor your water and fish closely during treatment. It allows you to quickly identify and eliminate any problems that may arise.

Even after you have eliminated Ich, your fish are still prone to other bacterial and fungal infections – so watch your fish closely in the weeks after treatment, until your fish have returned to full health.

While this may all sound like doom and gloom, recovery from Ich is very common. In fact, it’s one of the easier diseases to cure. If caught early, most fish make a full recovery.

Even so, the best way to beat Ich is to stop it from affecting your fish in the first place, which brings me to my next point.

How do you prevent Ich?

Tropical fish with early signs of Ich identified by white spots on fins

In my opinion, the best way to prevent Ich is to quarantine all the fish you buy before adding them to your tank…

Because that fish you just bought has been on one heck of a journey. Many fish we keep in aquariums come from the other side of the world. Even the ones that are bred locally make their way through multiple tanks before coming home with you.

During this journey, your fish will have plenty of opportunities to encounter Ich. While your fish may look good and healthy, she may already be infected with the early stages of Ich.

If you add this fish to your tank now, you risk everything in your tank being infected with Ich.

If you are serious about aquariums and plan on keeping fish for years to come, you want to set up a quarantine tank.

A quarantine tank is essentially an in-between tank for your fish to hang out in before you add him to your main tank. Most fish keepers quarantine their fish for 2 to 4 weeks.

During this time, the fish is treated for parasites with a copper sulfate solution.

Once your fish has been monitored and treated for a few weeks, you can add her to your main tank without the risk of introducing Ich and other parasites.

Now, I understand a quarantine tank isn’t going to be a practical solution for everyone. But in my opinion, it’s the best way to prevent parasites, fungal and bacterial infections from entering your main tank. It can also be used as a hospital tank when not being used as a quarantine tank.

The same goes for live plants, which should be treated before being added to your tank.

However, if you like to play things risky and skip the quarantine tank, there are other ways to prevent Ich…

Ich commonly infects fish that are stressed and in a weakened state.

So, If you eliminate stress, you can make your fish Ich-safe, right?

As if you needed another reason to stop stress, it’s the number one cause of death in fish.

Fortunately, keeping your aquarium stress-free is darn simple. In fact, much of it comes down to good housekeeping – things you should already be doing!

  • Cycling your aquarium
  • Not overstocking your tank
  • Stocking compatible fish and invertebrates
  • Testing your water quality
  • Keeping water parameters stable
  • Cleaning and maintaining your aquarium
  • Performing water changes
  • Not overfeeding your fish

Not too hard, right? These simple tasks will keep your fish happy and healthy.


Black neon tetra with Ich (white spot disease) on scales and fins

I know those white spots covering your fish from mouth to tail might look intimidating. But don’t worry, Ich does not have to be a death sentence.

If caught early and with proper treatment, your fish should be on the road to recovery in no time.

If it’s too late for treatment, you may have no other solution other than to euthanize your fish. I know it can be hard, but it may be the only way to stop your fish from suffering.

Many fish keepers consider Ich to be a rite of passage. If you are keeping fish, it’s only a matter of time before you need to overcome it.

And now that you have read this guide, you know exactly what to do.