Can Fish Become Immune to Ich?

Often called ‘white spot disease, ich is a protozoal disease. It is one of the most common diseases in freshwater and marine aquarium fish. It is a common nuisance as many hobbyists consider because when you have an aquarium, your fish will at some point get ich regardless of how long or short you keep them. Ich causes most fish death than any other disease.

There are various ways of treating ich in your fish. When this treatment is carried out effectively, your ich becomes free of the disease. The fact that this protozoan is widespread, makes almost all fish exposed to them.

They tend to develop immunity against the disease. They fight the infection before it gets to them. This article will give you a detailed explanation of ich, how your fish develop this immunity, and another important aspect to know as a hobbyist.

Can Fish Become Immune To Ich?

Yes, fish can develop immunity to ich infection. If your fish have survived an inch infection before, they can develop immunity to the parasite. They become resistant to a re-infection even if they are exposed to the parasite again. The mucus and serum of the fish will contain antibodies against the ich.

When there is contact between them ( the parasite and the antibodies), the antibodies will immobilize the parasite. This will make the parasite lose its swimming ability and cause it to leave the fish. This way the ich wouldn’t get established. 

How Do You Know Your Fish Has Ich?

Ich stays in the water for about a week before infecting your fish. You can treat the water and get rid of the ich at the water stage. Most times, ich infection is detected when it has already infected your fish and is already in its issue. You will notice white spots around their skin and fin, hence the popular name ‘white spot disease’.

Sometimes the white spot is only seen on the gills. Your fish will become easily irritated as the disease progresses. They try to rub and scratch against the sides and bottom of your tank. When not treated, it might cause respiratory distress, your fish wouldn’t eat, severe agitation, and death. 

Aside from the white spot on the skin and find, one can identify the infection using a microscope

How To Prevent Ich Infection 

When prevention is put in place, there will not be any need for a cure. Prevention is the best way of controlling and preventing ich infection. There is some preventive measure to take when setting up an aquarium to prevent ich in your tank entirely even before adding your fish. Some of these preventive measures are;

– Early Detection

This is very critical to prevent your fish from getting infected. Early detection means early treatment. For a new aquarium, you can use a microscope to check the water for the parasite before adding your fish.

If it happens to be present, you have to treat the water either by increasing the temperature or using other chemicals to treat it. When your fish is already in your tank, you need to monitor its behaviour every day to detect any changes, especially in the early days after adding your fish.

– Quarantine

Naturally, fish are parasite carriers. When buying your fish from the pet store, they might not show any sign of disease even if they have it. As a preventive measure, you need to quarantine your new finned friend in a separate tank from the one you plan on making your main aquarium for about a week.

This way you can easily monitor, detect and treat possible infections including ich before transferring your fish to the main aquarium.

– Decorations

You can add stones and rocks as decorations to your aquarium. They can also serve as filters for the removal of waste materials. Some of these stones will house colonies of bacteria (beneficial)  which can remove waste from the water.

Some of these stones and gravels are collected from rivers and streams. You will need to properly wash, clean, disinfect and air-dry them for a few days to avoid putting them in your aquarium with parasites that can be harmful to your fish.

Guide on How To Treat Ich Infection

As a new or long-time hobbyist, there is every need to know about treating your fish when infected with ich. When ich is treated, you will become free from the disease and will live a normal life. There are various ways of treating ich, depending on which suit you and what works best for you. They are;

– Chemical Treatment

This type of treatment is done when the parasite has already penetrated the fish’s skin and gills. Your fish has a low tolerance for chemical concentrate and can die. Treatment with chemical is always hard because the chemicals that will kill them has to be in high concentration and penetrate the fish tissue to kill the parasite.

Majorly, all anti ich treatment chemicals contain formaldehyde, copper sulfate, malachite green, or a combination of two of these chemicals. 

– Salt and Water Treatment

This is mostly done to kill the parasite right when they are in the water before they penetrate the fish’s tissue. Adding salt into the water can help kill them.

When using salt treatment, you do not add the salt directly into the aquarium water. You add it by making a salt and water solution. You can add 2-3 teaspoons of salt to a gallon of warm water.

– Temperature

Ich can survive in aquarium water for almost a week at 22°-25°C. Their life cycle lasts about 3 weeks at 9°-10°C. At the temperature of 24°-25°C, the life cycle is on 6 days. The higher the temperature, the shorter the life cycle.

Some hobbyists use the temperature to treat ich infection, leveraging on the parasites’ sensitivity to water temperature. You should hear your aquarium to 30°C for as long as your plan to treat the parasite. Make sure your fish can tolerate the temperature increase. If they can then, it is a good treatment option to consider.

How To Clean Your Tank After Ich

After treatment, there is every need to clean your tank. You can transfer your fish to a small temporary tank while you clean their main tank. Drain the water completely and add new clean and infection-free water.

Add a little ammonia and restart your tank’s filter, this will feed the biological filter and get them ready for your fish. Run the aquarium water for about a week at a temperature of 75°C. Check for ich in the water using a microscope. When all is clear, you can then bring back your fish to their home.


A fish that was once infected with ich can develop an immune response against the parasite. They develop antibodies that will render the ich immobile, leading to them losing their swimming ability.

There are various ways of treating your fish when infected with ich which include using salt or increasing the water temperature because they can’t stand a high temperature. You prevent your fish from ever having contact with ich to avoid the stress of treatment.

You can achieve this by buying healthy, non-infected fish and quarantining it in a temporary aquarium before transferring them to the main aquarium.