The Ultimate Guide to Treating Fish with Ich

Last Updated on 2024-07-02

Ich, short for Ichthyophthirius multifiliis, is a parasite that can infect fish and cause various health issues. Knowing how ich affects your fish and how to treat it if needed is essential. In this article, we’ll discuss the lifecycle of ich, what causes it, how to identify its symptoms, how to treat it, and how to prevent it in the future.

What Is Ich?

Ich is a parasite that lives on fish and can be found on their bodies, fins, and gills. If you don’t treat Ich, it will ultimately kill your sick fish. Ich is easily spread from one tank to another by fish, invertebrates, plants, decorations, or even maintenance tools like your gravel vacuum or nets.

These parasites, made up of protozoa, are small. Really little. In fact, they are so small that you have to use a microscope to see them. But you don’t need a microscope to tell if ich infects your freshwater aquarium fish. There are some clear signs that I’ll talk about later in this guide.

If caught early, Ich is easy to treat, and many fish get better. Ich is different from other fish diseases because it has a life cycle. This means that the treatment you give your fish needs to be long enough to break the entire life cycle of these parasites and eliminate them from your tank.

What Is The Lifecycle Of Ich?

Ich is a common condition affecting many fish, and understanding its lifecycle can be important for effectively treating infected specimens. Although it has a few different stages, the general lifecycle of Ich follows four distinct steps: the parasitic stage, intermediate stage, reproduction stage, and infectious stage.

1. Parasitic Stage

The Ich burrows into fish and eats the skin and tissue, which makes the fish uncomfortable. As it eats your fish, it makes a hole in the flesh. Your fish tries to eliminate the Ich by building a white, crusty wall around itself. It looks like a white spot is on this wall.

2. Intermediate Stage

Once the Ich is fully grown, it breaks through the white crust. It floats around, looking for a hard surface to attach to, usually the bottom of your aquarium. When the white crust covering the wound on your fish falls off, the wound is left open. At this point, your fish are more likely to get sick or get a fungus. 

3. Reproduction Stage

Once the Ich reaches the bottom of your tank, it makes a tomont, basically an egg. The Ich splits into hundreds or even thousands of babies inside the egg. These babies are called theronts. The babies inside the egg are secure from medication because the egg is sealed.

4. Infectious Stage

The theronts swim out into the aquarium’s water when the egg hatches. They swim around on their own and look for fish to hide in. The babies only have a few days to live. They will die if they don’t find a fish with the virus. During this stage, Ich is easy to treat with medicine.

What Causes Ich In Fish?

Ich is a parasite that can give your fish a lot of problems and kill them. Read this list to find out the most common reasons why it happens.

1. Poor Water Quality

Many things can make fish sick if their water isn’t good. It stresses out your fish and makes them much more likely to get sick or catch diseases. This is because stress weakens their immune systems, making it easier for them to catch parasites and bacteria like ich.

2. Fish Tank is Too Full

If you have too many fish in your tank, your fish can easily get Ich disease. Fish without room to swim aren’t as happy and healthy as those that do. This makes it more likely that they will get sick and spread diseases to each other.

3. Improper Diet

If your fish isn’t getting the right diet for their species, it can make them more likely to get sick. Make sure that you are feeding your fish a balanced diet that is made for their species and size.

4. Contamination

Ich disease can easily spread to a new fish tank through several different means. It could come from things you put in your fish tank that is already infected, like the substrate, aquatic plants, and decorations. Fish can be sick of Ich before they show symptoms, so you may have brought a sick fish home.

5. A Change In Temperature

Ich is often spread when the water gets too warm or too cold. Make sure to keep your tank at a stable temperature that falls within the range of your fish species. If it changes too fast or dramatically, it can cause stress in the fish and make them more susceptible to diseases like Ich.

6. Cold Aquarium Water

When your aquarium is cold, it can be very easy for parasites to make more of themselves. This makes it more likely that your fish will get an Ich infection. Even if you have a heater for your fish tank, the temperature outside will still affect your fish. 

7. Stress

Anything that stresses out your fish can make it more likely to get an Ich infection. Stress can cause a fish’s immune system to become weaker. It also makes the fish lose its appetite, slows down its metabolism, and makes it even less able to fight disease.

What Are The Symptoms Of Ich In Fish?

Ich lives under the fish’s skin and eats their body tissue, so treating them as soon as possible is important. Look for these signs if you think your fish has an ich infection.

1. Spots of White

If it has ich, your fish might have white spots all over its body. Ich is eating the flesh of your fish, which is why it has white spots. But if most white spots are near the gills and front fins, your fish is probably a male and ready to breed.

2. Lethargy

If your fish has ich parasites, it will try to hide and stop moving around as much. This happens because fish instinctively try to hide when they don’t know what to do, are scared, feel uncomfortable, or are stressed.

3. Fin Rot

Ich is a tiny parasite that lives on the fish’s scales and fins and feeds off them to get the nutrients it needs to make more of itself. When this happens, the fins and scales get hurt, and they will eventually start to rot.

4. Loss Of Appetite

One sign that your fish has ich is that it doesn’t want to eat. This is because an ich infection can make the animal feel stressed, causing it to lose its appetite.

5. Cloudy Eyes

Ich gets in through cuts or even the eyes, where they release their digestive enzymes. This can cause damage and inflammation to the eye’s tissues, clouding the fish’s eyes.

6. Pale Color

A pale-colored fish usually means the water has too much ammonia and nitrates. But ich can also make your fish lose its vibrant color. If your fish’s color changes, it’s usually about to die, so you should treat it immediately.

7. Clamped Fin

Fin clamping is also another common sign of an Ich infection. This is when the dorsal fin is pressed against the body. Sometimes, fish clamp their dorsal fins down when doing certain things or swimming in a certain way. This is normal, but if you find that your fish is always clamping its top fin, this is usually a sign of stress and illness.

How Do You Treat Fish With Ich?

When your fish has Ich, it will stress them out so much that it can lead to other health problems. When Ich gets into your fish, they need to be treated as soon as possible. Follow these easy steps to treat Ich in your fish.

1. Change The Water

Change at least 25 percent of the water in the tank and eliminate any floating waste. You can also lower the water level in your aquarium to make the water surface move more. When you add the ich treatment later, this will help move it around the water.

2. Take Out The Activated Charcoal From The Filter

When you change the water in your aquarium, remove the carbon filter because the activated carbon will make the medicine useless. You can remove it and replace it with a filter that moves the water mechanically. This will also help spread the treatment for Ich through the water.

3. Raise The Temperature Of The Water

The temperature of the water is raised not to kill the parasite with heat but to speed up its life cycle. You are trying to speed up the process of each parasite getting to the point where it can swim freely so that the Ich medicine can kill them without hurting your fish. Ensure you slowly raise the water temperature to not shock the fish.

4. Make Sure There Is More Oxygen In The Tank

When it’s hot, your fish can move around more, so they need more oxygen. If your fish has Ich, it may also have a damaged gill that makes it hard for it to breathe. You can fix this by putting air stones or an air pump in your aquarium.

5. Take Your Medicine

You can buy a lot of commercial treatments for Ich online or at a pet store near you. These chemicals, like malachite green, methylene blue, and copper, are usually safe for aquariums. Note that copper-based Ich treatments can hurt other animals or plants in the aquarium.

6. Add Aquarium Salt

After you’ve taken care of your fish tank, you can add aquarium salt. Slowly letting oxygen into the water is how the salt cleans it. It also makes it easier for parasites to leave the fish’s skin. Aquarium salt makes it easier for fish to breathe, which helps them stay healthy. It also thickens your fish’s slime coats and kills Ich faster.

7. Wait For The Ich To Die Off

The Ich medicine might take a while to get rid of the parasites in the tank because each parasite must swim freely before it can be killed. After two weeks, your fish should no longer have white spots, and there shouldn’t be any Ich in the tank. If your fish still has Ich after two weeks, you might need to take it to a vet.

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How To Prevent Ich In The Future

As aquarists, it is always our job to ensure our pets are safe and not in danger. It also keeps us and our pets from getting too stressed out. Here are some things you can do to make sure your fish don’t get ich.

1. Clean Everything Before You Put It In The Aquarium

If you put something in your fish tank already infected with Ich, it can spread to your fish. Ich can spread on water plants, decorations, and substrate that hasn’t been cleaned. Before you put anything in the tank, make sure it is clean and free of germs.

2. Always Put New Fish In A Quarantine

Ich can also come from new fish that you add to your tank. Setting up a second fish tank to be used as a quarantine tank is highly recommended. So, you can closely monitor your new fish to see if they have any diseases, parasites, or bacteria or if they are healthy enough to go into your aquarium.

3. Keep The Water Quality High

Ich can grow in many places, but aquariums with bad water are the best places for them to grow. Make sure the water in your aquarium is always clean by doing partial water changes, adding a filter, and adding live plants.

4. Do Not Overstock Your Tank

When you have a lot of fish in your aquarium, they have less room to swim and make more waste, giving off ammonia and nitrate. This will lower the water quality in your aquarium, letting ich live and grow.

5. Feed Your Fish Good Food

Always feed your fish different, tasty, and healthy food. This will not only keep them happy and healthy but will also make their immune systems stronger. A healthy fish may also have a healthy slime coat that helps protect it from Ich.

6. UV Light

UV lighting is one way to stop ich from growing in your fish tank. UV sterilizers can’t kill ich that is already on a fish, but they can be killed while the ich is free swimming. This makes it less likely that Ich will stick to your fish.

fish in an aquarium . In the park in nature

What Is The Best Ich Treatment?

Copper-based medicines are the best way to treat ich. Instead of treating the main tank, move the sick fish to a quarantine or treatment tank with a bare bottom. This should have aeration and water conditions that are the same as the main aquarium.

However, there is no one-size-fits-all answer to this question because every aquarium and fish is unique. You can try over-the-counter medicines, aquarium salt, and UV light. But if your fish is still not improving, you may want to take them to the vet for professional treatment. 

Make sure to properly clean your tank and add quarantine tanks when introducing new fish to avoid Ich in the future. Ich can cause a lot of stress and health issues in your aquarium, so be sure to take measures to prevent it.  


Can Fish Heal From Ich On Their Own?

Saltwater fish have several natural defenses against ich. If the fish are healthy enough and the outbreak is mild enough, they can sometimes heal themselves, just like they would in nature. We can help them in some ways by ensuring the water is clean and giving them food that is good for them.

What’s The Fastest Way To Cure Ich?

The fastest way to cure ich is using copper-based medicines in a quarantine tank. Ensure you follow the instructions carefully, as over-medicating can harm your fish. It’s best to talk to an experienced aquarist or a veterinarian to make sure you are giving the right medication.

Can A Fish Survive Ich?

Yes, fish can survive ich if you start treatment early enough. However, it is important to note that the Lifecycle of Ich is very fast, and it can spread quickly in your aquarium if not treated correctly. Start treatment immediately if you think one of your fish is showing signs of Ich.

Can Ich Affect Humans?

Yes, people can also get Ich. But it doesn’t happen as often. Ich is more likely to spread to fish, so many people who keep fish will treat their tanks if they see white spots on their fish. 


Ich is a parasite that can cause serious health issues in fish. To properly treat your fish and get rid of Ich, you must do the above-mentioned steps. You must clean everything before putting it into the tank, quarantine new fish, maintain good water quality, and not overcrowd your tank. Feeding them healthy food can also help strengthen their immunity and prevent Ich. Keep your fish healthy, and you’re sure to have a happy and healthy aquarium.

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