Fish Ich – White Spot Disease

Together with fish, shrimps, plants, or snails inside, aquariums are a passion for many people. Sometimes, the aquarium for hobby purposes or commercial purposes may encounter some problems. The most important of these problems are diseases that affect aquarium creatures. These diseases can cause both large economic losses and the death of the living creatures in the aquarium. In this article, we will be focusing on the Fish Ich (the white spot disease) that is very common in fish and causes significant losses.



The root cause of the white spot disease is a parasite called Ichthyophthirius multifiliis or shortly known as Ich, which mainly affects tropical fish. Once this parasite enters the aquarium, it can spread so quickly. It can reach 100% mortality with rapid spread if there is no control. Unfortunately, no fish have complete resistance to the Ich parasite and for that reason, all new fish must pass through a quarantine period before introducing to the main tank or the facility for larger-scale commercial establishments.


This parasite generally has three life stages that are respectively parasitic, reproduction, and infective stages. In the parasitic phase, the parasite attaches to the host fish and lives on it until it kills the host in serious infections (too many parasites exist on the fish) or treated somehow. During the reproduction phase, the parasite separates from the host and attaches to the aquarium bottom or other substances. Here it builds a cyst wall and begins the reproduction. It can reach from one parasite to a thousand parasites in this phase. After attaining the required maturity, they come out of the cyst and look for a suitable host in the aquarium. This stage is the infection stage. The parasite, which cannot find a host for itself within 2-3 days, dies. If it finds a host, it clings to the host and makes starts draining the host’s blood. In case there are many parasites in the aquarium, and the treatment is delayed or not applied, all the livestock may die.

There are some theories about why fish get infected with this disease. The first of these is sudden and unexpected environmental changes. Sudden and significant changes in water temperature are one of those situations. In those cases, the mucous layer of the fish gets hurt. Thus, the parasite can find the chance to attach itself to the host’s body. A second reason is poorly established aquariums with low water quality. Such improper conditions also cause the same harm in the mucous layer of the fish and make the fish vulnerable to infections including, but not limited to Ich. Almost any aquarium creature can live healthily in well-established aquariums. If the aquarium conditions are not adequate, diseases such as white spot disease may occur. Another reason to be most careful is the things put into the aquarium. Rocks, woods, decorations from other aquariums, or sources can carry parasites to the aquarium. These materials placed in the aquarium without passing through necessary cleaning processes may cause disease for fish.


It is a disease that is very easy to detect visually. The most prominent symptom is the white spots, which also takes its name. These white spots occur in various amounts on the fish’s body. These spots, which are less and small at the beginning of the disease, increase and grow as the disease progresses.

On the other hand, this disease causes some disorders in the fish’s behavior. The most common of these are the attempts to scratch on the rocks, gravel, or decorations. At this stage, irregularity is noticeable in the swimming of the fish. Lethargy in fish and redness of the skin are also symptoms of advanced stages of the disease.

Treatment and Prevention

First of all, a complete quarantine to the tank should be applied when a sick fish is detected. Since the disease spreads very quickly, being late in quarantine application may cause the infection spread on other fish and other aquariums to become infected by any possible transfer of water, decorations, or equipment.

After the tank is quarantined, treatment with medication should be started immediately. The most significant point on that is the parasite does not respond to the medication at all phases of its life cycle. If the parasite has entered the fish tissue, medication will not work. The most suitable stage is the reproduction stage of the parasite for the effectiveness of the treatment. In higher temperatures such as 29-30°C the parasite passes to this reproduction phase more rapidly. Thus, before the first drug treatment, increasing the water temperature will improve the efficiency of the treatment. After increasing the temperature to 30°C, treatment with commercial Ich drugs or anti-parasite drugs containing substances such as formaldehyde, malachite green, or copper sulfate will solve the infection issue.

The malachite green treatment has some disadvantages. According to reports, some fish species may not be able to tolerate this treatment. Scaleless fish are sensitive to malachite green and treatment may kill these fish. Medication should take 10-14 days to ensure that all parasites are killed. 25% water changes every day during the treatment is also substantial. During the water changes, siphoning the substrate will ensure the removal of dead or weak parasites from the aquarium. Since the medications to treat fish ich are widely available in the market, it is better to buy one of them rather than preparing your solution without a specialist’s instruction for the dosing of chemicals.


It is more important and easier to prevent the disease than to treat the disease. White spot disease is an easily preventable disease. Like other diseases, stability is significant in prevention. Water pH level, temperature, and water quality must be maintained at optimal levels. For this, there should be a heater and a thermostat in the aquarium. For good water quality, a proper filter with sufficient biological and mechanical filter media will be simple and enough. Changing the aquarium water regularly is another critical point to ensure high water quality. Water quality is essential not only for disease prevention but also for fish to live longer and healthier.

If new fish or plants are to be added to the aquarium, their health should be checked at the time of purchase. Aquarium creatures that come infected from outside can well spread any disease. When a new fish, plant, or material is received from outsources, keeping them in quarantine for two weeks before placing them in the aquarium is one and the easiest of the measures that can be taken at first. Rocks, wood, or other decoration items must be correctly disinfected or cleaned before using in the aquarium. In this cleaning phase, a parasitic disinfectant, rock salt, hot water are suitable to use.

In summary, the most significant issue in diseases is the daily control of fish for any symptoms. Diseases such as white spot disease have easily noticeable visual symptoms. So, action can be taken quickly. Quarantine of infected fish is always significant but a total treatment to the tank is more efficient since some parasites, bacteria or other causes may remain in the tank and may cause the disease to recur.

Note: Any treatment should be started in consultation with a relevant expert or veterinarian.

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