How Fish get Ich? How Do You Treat Ich on a Fish?

Fish are delicate, tiny, and beautiful creatures. If you own fish, the last thing you want is for the fish to be killed by a skin infection, that too because of your lack of information.

Sadly, Ich is a very common fish disease. Fish that have a weak immune system are prone to attack by this parasitical infection. Stressed fish are also likely to get Ich. Moreover, it is a contagious infection that will spread from one fish to another. Luckily, this infection is easily treatable with the right medicine and care.

If you want to keep your fish safe from the risk of developing Ich, you should learn all about the parasite. I’ve mentioned the preventions, symptoms, and treatments below for your convenience.

Treat White Spot Disease in Fish (Video)


What is Ich?

Ich, or ick, is the short form for Ichthyopthirius multifiliis. You might know it as the white spot disease in fish. The name means ‘fish louse with many children’ and this is a spot-on description of the condition. It is a skin infection but one that can prove fatal. The first step to tackle this parasitical infection is to know all about it.

Here’s the thing:

As you may have already guessed, the fish develop white spots in this condition. Each white spot is basically a parasite that has found home on your fish’s skin. The spots look like a grain of salt and are nodules of around 1mm diameter.

This widespread disease is one of the most common fish diseases, especially in freshwater fish. The parasite that attacks the fish has the ability to reproduce immensely. Moreover, the haunting part is that every single parasite on the skin is actually eating your pet. But that’s not all. This is just the first step. These parasites have a repetitive life cycle that can wipe your entire fish tank dead.

Life Cycle of Ich

In the first stage, the parasite is a protozoan. This is an active stage where the ich feeds off of the gills or skin. The white spots you notice on your fish are identification of this stage. Naturally, the immune system of the fish keeps fighting against the ich. To tackle this problem, the white spot will keep moving around, eating your fish from different areas.


The parasite transitions to the second stage. During this time, the parasite is a reproductive trophont. This is when the parasite will fall off from the skin of the fish. You may think the issue is over now that your fish are safe. But guess what, the situation has only gotten worse. This is the stage when the parasite will divide into numerous parts, reproducing more of its kind.

Each trophont will stick to ornaments, gravel, plants, or any other surface in the fish tank. They divide into hundreds and thousands of tomites. When the trophont is done reproducing, the new tomites are released into the water. These tomites can survive on their own for up to 48 hours. If they don’t find a fish to feed on within this time, they will die. However, if they successfully attack a fish, the cycle will restart all over again.

There is an optimum temperature range required for this cycle to take place effectively. Also, this entire process happens in 4 to 7 days. You can utilize this information to treat your fish tank accordingly.

Symptoms and Identification

Since this infection can be fatal, it is extremely important to identify the condition as early as possible. Fortunately, the symptoms of Ich are very noticeable and easy to identify.

Of course:

The most evident one is the appearance of white spots on the skin of the fish. Nodules of 1mm that look like grains of salt can be noticed all over the body, including the gills. Although these spots are quite visible, you can also opt for a microscopic test for 100% assurance. The parasite is scraped off the body. This leaves behind a cyst on the skin of around half a millimeter depth. Under the microscope, the parasite will have a horseshoe-shaped nucleus.

Other symptoms won’t be noticeable immediately. Also, since fish aren’t like other pets, other symptoms are harder to identify. But one that you can notice is that your fish will feel itchy. This leads to unusual behavior. You’ll notice it scratching the body against plants or other surfaces. Moreover, the fish won’t appear as active. The irritating and painful Ich will make the fish lethargic too.


As the gills are attacked by the parasite, it leads to respiratory issues. Rapid breathing is an indication that the Ich has gotten to the gills even if the spots aren’t visible in that area. What’s worse is that this condition can also cause slow respiration. This causes the fish to lay down and rest unusually.

Other indications of Ich are that the fish will lose appetite. You’ll notice extra food resting on the bottom of the fish tank. The fish will, of course, become anorexic due to this. Schooling fish will stop schooling when affected by Ich. The infected fish will hide for most of the day and won’t swim normally. They may swim upside down on the surface of the water.

Causes and Prevention

So basically:

Ich is a parasite that exists in the environment. You cannot really kill or eradicate the risk completely. However, of course, you can minimize the chances. This can be done by tackling every aspect that may cause your fish to be affected.

The thing is that all that is in your control is the state of the fish’s immune system and the environment of the fish tank. You cannot control more than that. So, therefore, you should look at the list of causes that are making your fish prone to attack.


A weak immune system is a prevalent factor in all fish that are attacked. These fish are unable to save themselves from attack. A weak immune system is a result of stress in most cases. It may also result from a previous illness. To eradicate the latter risk, you need to be vigilant in terms of providing a relevant and effective treatment whenever your fish are feeling sick.

Moving on is the more important step of keeping the fish stress-free. Bear in mind that fish are highly sensitive creatures. Literally, the minutest of changes can cause tension. A shift in water temperatures, overpopulated tank, rapid change in water composition, lack of nutritionally balanced food, and what not! The possibilities of stress-causing factors are endless.

Other reasons why Ich may have attacked your tank are that you purchased an infected fish. There is a possibility that you added a decorative item in the tank that was home to the parasite.

Long story short:

You shouldn’t be a good pet owner. Instead, you need to be the perfect aquarist to maintain a healthy fish tank.

Steps to a Safer Environment

A peaceful fish tank is perfect in terms of population, cleanliness, and water composition. The most common rookie mistake fish owners make is overcleaning the tank. You don’t have to scrub the tank every week. In fact, deep clean it only once a while. I’d recommend adding gravel and a filter to your fish tank so that the water doesn’t get messy often.


Never take the risk of keeping infected decorations or fish in a clean tank. Parasites like Ich attach to plants, gravel, and other surfaces. To prevent these factors from affecting your healthy fish tank, you’ll have to add a couple of extra steps to the process. In the case of non-living items, you can clean and sterilize them. The parasite cannot survive longer than 48 hours on these surfaces. As for new fish, you should check them thoroughly before the purchase. Another thing you can do is to keep new fish in a quarantine tank for two weeks. When you’re sure that the fish is clean, only then add it to your bigger tank.

Another important aspect to minimize stress in fish to prevent your fish tank from getting crowded. On top of that, do not keep breeds together that do not have the same level of dominance. Plus, you should never change the entire tank’s water at once. This causes a sudden shift in the chemical composition, which leads to stress in fish.


Ich is a very common fish disease. Alongside this, there is enough knowledge about the parasite. What’s even better is that the easily identifiable symptoms allow owners to spot the infection in the early stages. Altogether, these factors make Ich easy to treat.


There are quite a few treatment options. You can choose the one that suits your fish breeds and fish tank the best.

The first treatment option is to remove your fish from the tank. Trophonts need to attach to a living fish within 48 hours to survive. After you remove the fish and put them in a clean tank, raise the temperature of the infected tank to 80 degrees Fahrenheit. This will automatically kill the parasites.


If you have infected fish, the new clean tank will also get infected. To prevent this from happening, you will have to first disinfect the affected fish. You can try the heat treatment in case you don’t have cold-water fish in your tank. Raise the temperature of the water to a point that is suitable for the fish but will kill the parasites.

Another remedy for such a case is to use salt. It isn’t a suitable treatment if you own soft water fishes. Otherwise, you can add up to 5 grams of salt per liter of water to kill Ich. This treatment should only be used in infected tanks. If you use it as a preventative, there is a risk that the Ich will develop a resistance against it. You can use the heat and salt treatment side by side too.

You can try all the aforementioned options at home. But, if things have gotten out of hand, you’ll have to head to the vet. In this scenario, you’ll be suggested certain medicines. With the help of these chemicals, Ich can be eradicated even if it advanced to stronger stages.

Related Questions

How long does it take for Ich to kill a fish?

Ich is easily treatable once spotted. However, keep in mind that it is a parasite that reproduces at a fast rate. If you leave the condition untreated, your fish will eventually die. It can take anywhere between 5 to 7 days for Ich to kill a fish if ignored.

Is it okay to keep a fish tank in your bedroom?

Technically, there’s nothing wrong with keeping a fish tank in your bedroom. However, when you consider the pros and cons, it is best to keep the fish in a separate room. One major issue is that fish, water, and devices such as air filters; all make noise. This will disturb you. Moreover, you’ll have to define your schedule of turning the lights on and off according to the fish’s requirement. All in all, it isn’t a feasible option.

Can fish ick affect humans?

There a number of fish diseases that can transfer to humans. This usually happens while cleaning the fish tank. Ick, too, can transfer to humans. But, the good news is that it doesn’t really affect humans the way it affects fish. Even if the parasite transfers to your skin, you won’t suffer from any negative impacts.

Can a dirty tank kill fish?

Of course, a dirty environment is never healthy. But, the risk of fish dying in a dirty tank is lower than the risk of fish dying if you suddenly decide to clean the tank. The reason being that fish need time to adjust to their environment. The fish get used to the dirt in the tank as it builds up slowly. But, when all this dirt will suddenly be replaced with fresh, clean water, the shift in the environment will be major, and the fish will die of stress.

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