What Causes White Spots on Tropical Fish


Do you know about Ich? Short for Ichthyophthirius multifiliis! This parasite is what causes white spots on tropical fish. After these parasites have been discovered in an aquarium, they reproduce rapidly that the illness is almost impossible to eradicate. In this article, we’ll discuss several effective methods for treating white spots in fish and some frequent reasons worth being aware of.


When a protozoan lives on an aquarium fish’s body, fins, or gills, it causes a white spot. Tiny white spots all over the body of the fish are the first sign of the infectious sickness. These parasites, which resemble tiny grains of salt or sugar, may disrupt a fish’s respiratory system and create movement issues. There are two phases of the parasites that produce a white spot in fish. During this first “free” period, the parasites will multiply fast. During the second phase, the parasites will eat away at the sick fish’s tissues.

At this point, the parasite has invaded the host and is ready to enter the body via any openings in the skin. When the parasite has done eating and infecting the fish, it will descend to the bottom of the tank, where it may proliferate by making up to 2,000 offspring. It’s clear to see how quickly the disease may spread across a population of fish that was previously healthy.

Fish in an aquarium will all die if a tank infected with a white spot is left untreated. Fish afflicted with white spots will exhibit symptoms such as erratic behaviour and folded fins in the early stages of the disease.

Causes of white spots on tropical fish

It’s important to be aware that White spots may be provoked by stress brought on by sudden changes in climate. Parasites in fish tanks are common, but a healthy fish’s immune system can usually defeat them.

Ich is a parasite that may live dormant in an aquarium or be brought in by new fish. Powerful fish immune systems allow them to maintain the parasite-host equilibrium for a long period. Parasites have a hard time reproducing since they can’t infect healthy fish, which helps keep parasite numbers in check.

Parasites may flourish on the tank’s newcomers. The strain of travel and adjustment to a new environment might have weakened their immune system. as a result, they are easy prey for the parasite.

Let’s suppose Ich suddenly appears in your tank, but there have been no recent additions. In such instances, it might be due to water conditions or a crowded tank, both of which can lower fish resistance to disease.

Besides those already mentioned, the following may also contribute to the development of white spot disease:

  • Not properly quarantining new fish
  • having too much waste, and too much ammonia and nitrates in the tank
  • Changes in pH, low levels of dissolved oxygen, and contaminated tools
  • Raw Decoration
  • Bad upkeep and lack of cleanliness

Signs and symptoms

The parasite responsible for Ich is very contagious. If your fish has Ich, how can you tell? White spot disease is not usually noticeable to the naked eye, and its early stages may be easily confused with those of other illnesses. If your fish exhibit any of the following signs, Ich is likely the cause.

  • Having a white patch on the fish’s body is an indicator.
  • White dots or spots might suddenly emerge on the gills, gill covers, body, head, and fins of a fish.
  • Rubbing or scratching against the aquarium’s décor or substrate.
  • Apathy and/or a lack of appetite (moderate).
  • Strapping the fins to the midsection (advanced).
  • Floating at the tank’s surface, gasping for oxygen (advanced).
  • Bruising and sores all over the body, head, and fins that ooze blood (advanced).

In most cases, the onset and progression of Ich occur simultaneously. The difficulty is compounded by the fact that not all ill fish have white patches. In the case of minor infections, the parasites may simply be lurking in the gills, where they can’t be seen. The modest symptoms may not become obvious until other fish begin to show illness.

What causes white spots on tropical fish | Credit: liuyushan

Tips for preventing white spots on tropical fish

  • Make sure the conditions in your tank don’t fluctuate wildly by keeping up with regular water changes and filter maintenance.
  • Use a heater to keep the water temperature steady and avoid overfeeding or feeding your fish irregularly to reduce the stress caused by changes in the water’s conditions.
  • Never introduce new fish or live plants to the main aquarium without first quarantining them for at least seven to fourteen days (or longer for coldwater species).
  • At the first indication of disease, sick fish should be removed to a separate hospital tank.

How to Deal with White Spot Syndrome

Fish recovery from white spot disease? Ich is a complicated illness, and not all infected fish will recover. The severity of the issue and the harm caused by the protozoan are also factors. However, if a fish makes it through an illness, there’s a strong chance it will develop some resistance to it.

Stress-inducing and poisonous drugs compound the difficulties of treating Ich. Ulcers on an infected fish’s body may lead to secondary infections, requiring antibiotic treatment. In this short article, we will examine the means by which white spot illness is managed in aquariums.

Medications such as malachite green, copper sulfate, and others

Some aquarists still employ the traditional method of treating Ich, which involves dosing the tank with a poisonous mixture of chemicals like malachite green, copper sulfate, or other parasite remedies like formaldehyde for 7 to 14 days. Fish skin is impermeable to these medications; thus, they should be administered during the fish’s free-swimming phase.

To treat the whole aquarium, you must first remove the chemical and biological filter media and make 25% water changes every day. You may get rid of a lot of parasites in stages 2 and 3 by vacuuming the gravel. Instead, you may utilize a hospital tank to treat individual fish if just a few are sick.

 Aquarium salt

Increasing the salinity of your water with non-iodized aquarium salt is another approach that has had some effectiveness. This may help alleviate your fish’s itching from the cysts and eliminate the free-swimming parasites. While medicating your fish, you should remove all filter media and do regular water changes.

You need to learn what salinity is best for the aquarium inhabitants you want to maintain. Some fish are very sensitive to saltwater and could die if even the recommended amount is introduced to their environment. Salinity should be kept constant for at least 7–14 days.


Prevention of Ich, a frequent but difficult issue in freshwater aquariums, is preferable to treatment. It’s unfortunate that many therapies add more stress to an already difficult situation, and not all infected fish make it. However, following the advice in this manual may cut down on tank deaths and prevent the issue from occurring again.


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